Those who keep the factory AC - Do you use it?

[A_Bus_Called_Quest]

Originally Posted by cadillackid

Tjones has it right.. the EM-3 evaporator has 2 separate A/C systems within it so a side nit blowing full cold could be l;ow on freon or maybe the underside fans are not running correeclty or dirty coils outside for that one system..

that orange wire is the MAIN blower wire feeding the resistor pack for high speed.. either one or more of ther blower motors are failing and pulling more current than they should.. ie bearings going, windings have too much resistance.. or like Tjones said the terminals could be not making great connection.. id bet a good first step is to see if you can clean up the terminals on those blocks and see if its any better..

those resistor blocks themselves can get pretty hot.. that orange wire looks like a single 10 gauge feed wire.. thats pushing it for 3 motors.. I ran a #8 for my 2 motor system...

I tried to attach the wiring diagram of what I believe you have installed.. a carrier EM-3 I believe inside unit.. someplace will be the relay panel thats referenced in the bottom of the drawing.


Attachment 60252

Originally Posted by TJones

I am not as knowledgeable as Cadillackid but I can try to answer your questions. If each evaporator is has separate lines to its own compressor it may be that half of the system is low on refrigerant.

The hot wire could be several things. I would first check to see if it is hottest at the crimped terminal. A bad connection there could generate extra heat. If the wire seems to be warm a good distance from any connector. I would suspect a component drawing more currant than it should or short. However if the wire is carrying more currant than it should I would think that a fuse on that curcuit would have blown. Also check your blowers and see if they turn freely. Added resistance from being dirty or a bad bearing would cause a motor to draw more currant.

Ted

TJones and CadillacKid - Thank you both for the info on the wire and blowers. I went out and cleaned all of the terminals for the AC unit, and replaced the female end to that 10# orange wire - so far it seems to have solved the hot-wire issue. I let the bus run with the ac for a while and no temperature change in the wire, whereas last time it heated up almost instantly when I turned on the AC and even melted part of the plastic insulator sleeve!

I haven't had a chance to inspect the left vs. right blower yet - quick question though. Are both compressors running off of the engine up front? See attached photos - I posted these in a different thread about an engine-knock (Fixed!) and someone said they are the AC compressors. Seems to check out, the black hoses run out to the back of the bus, and to the AC unit.
Seems like those wires are disconnected? Black vs Red . . . but do you guys see anything suspicious about this?

I've been crushing the interior - next week I will be back on the exterior and will check out the blower fans under the driver side.

If low on Freon - can I fill that myself, or better left for a pro?

[TJones]

Yes those are your AC compressors. The one that is unplugged is the side of your evaporator that is not cold. The wire could have come loose or was disconnected on purpose. With the engine off see if you can turn the compressor over by hand to make sure it isnt seized up. If it is free reconnect the wires and try it.

You can recharge the refrigerant yourself. You will need a manifold gauge and have to do some research on how to connect it and the test procedures and pressures for your system. If the system has 0 pressure then you likely have a leak and will have to find and repair the leak, replace the filter/drier, put the system under vacuum and recharge it.

Ted

[A_Bus_Called_Quest]

Originally Posted by TJones

Yes those are your AC compressors. The one that is unplugged is the side of your evaporator that is not cold. The wire could have come loose or was disconnected on purpose. With the engine off see if you can turn the compressor over by hand to make sure it isnt seized up. If it is free reconnect the wires and try it.

You can recharge the refrigerant yourself. You will need a manifold gauge and have to do some research on how to connect it and the test procedures and pressures for your system. If the system has 0 pressure then you likely have a leak and will have to find and repair the leak, replace the filter/drier, put the system under vacuum and recharge it.

Ted

Thank you for the info and advice! Good tip on testing the compressor by hand before plugging it in and trying it live.

[A_Bus_Called_Quest]

Alrighty - finally got out for some more AC diagnostics:

Both sets of undercarriage fans activate and run no problem.
The belt on the disconnected, second AC compressor (on the motor) has a good looking belt and spins with the motor.
However, when I reconnect the wire to the AC compressor and tur on the AC cold, an awful screeching comes from up in the engine, assuming from the compressor.

My guess is that I need to replace this part, but will need to drain the freon first so I can disconnect the hoses?
Is this an easy DIY or better off calling in the pros?

Thank you guys for getting me this far!

[cadillackid]

yeppers sounds like a locked up compressor..

to fix it


1. recover the freon out of the system (requires a refrigerant recovery machineand tanks or have a shop do it).


2. disconnect and remove compressor.. get a clear glass or cup and pour the oil out of the compressor. if the oil is nice and clear and doesnt have bits of metal in it then you are scott free, if its grey or filled with metal the nthe system needs fully flushed. draining oil on a busted compressor is a bit tough as it can be turned.. so rocking it around and pouring oil out of the freon ports and also out of the drain plug hole (if it has one) usually works. save the oil. we will need to know the amount if its clear. also note the inside of the pipes right near the compressor if you stick your finger in and it comes out black and grimy flush the system. if its mostly clean you are golden.



3. obtain a new receiver / dryer. without seeing your existing one (usually on or next to the underbody condenser) i cant say what to get.. they are pretty common and will be a cylinder shaped device 6-8" long. with a freon line coming in and out. blue or black.


4. obtain new compressor. the old one should have a tag of some sort ( I didnt read back through the thread you may have pictured it).. based on that a suitable part number can be found..



5. if the oil is clear and your new compressor ships with an oil charge then drain it into a new cup(if the compressor has a drain plug on the body unscrew it.. slowly rotate the compressor and rock it a bit until it seems most all oil is out.. (you can skip this step if you had to flush the system).


6. calculating the system oil is rather complex unless it is tagged someplace.. many installers Tag the amount of refrigerant and amount of oil required on the bus.. you always hope you can find this tag otherwise its time to get the math book out or find a system similar to yours and add that much oil.. I wont go into the math for it here.. not enough oil and you nuke a new compressor.. too much oil and the thing loses capacity and may liquid slug the compressor.. its not a mission critical thing so you can be off a little and be OK.. but again i didnt re read thread to see the exacts of your system.



back to oiling if you arent flushing the system then pour in the same amount of new oil back to the compressor that you pulled out of the old.. so if you drained 1.5 oz from the old compressor pour 1.5 oz new oil back into the new compressor.


if you flushed your system you leave the factory oil charge in the new compressor.


7. install new compressor and replace the O-rings when doing so.. put on the belt but dont plug the wire in yet.



8. remove the old receiver/ dryerand match it up to your new to make sure the new will fit. pour 1 oz of fresh refrigerant oil into the new receiver / dryer and install it.. use new O-rings. (this step should be completed at the same time your system will be evacuated and charged. the receiver / dryer has a dessicant, the least time it can spend in the air the better.. os I always replace it last and replace it after I have my vacuum pump and gauges connected ready to go).


9. Evacuate the air from the system using an HVAC vacuum pump.. 500 Microns is what I shoot for but 750 or 1000 is fine for an R-134a system.


10. Charge it up. (assuming vaccum holds for 30-60 minutes) I like to weigh-charge in the first portion of the charge. I also like to do this with a high system load.. so a day over 80 in the sun where the bus has hot -soaked.. Ill open all the windows or most of them and the doors so the system stays under load. I start with engine OFF and A/C OFF. I Punch in pure Liquid through the HIGHJ SIDE port for as much as it will take.. this is fast and usually gets a few poounds in. in case its taking lots ill stop at about 1 lb under tagged charge amount. otherwise once scale stops I close my gauge valve.



wait about 2 minutes then I plug the wire in on the compressor, start the engine and set the A/C to Maximum settings.. set the idle speed to 1200-1500 RPM.



I observe the system and will slowly bleed-charge in the rest of the refrigerant.. that last pound I will wacth the site-glass if one exists and also monitor my Superheat. I want to see my Suction pressure Match pretty close the Saturated Temperature.. so I measure evaporator temp at the inlet after the TxV and at the outlet.. a fully charged system will find its temperature at the evaporator midsection matching that of a PT chart pretty close in pressure.. thats the refrigerant temperature inside the pipes will match so its expected that the pipes may be a degree or so warmer than the substance in them... dont measure the air temp.



enjoy your ice cold A/C.


sound complicated? you can always wing it and charge the system till the suction line is cold and hope for the best. or you can send it to a shop.



im giving you the ideals for long lasting ice cold A/C.. then again im an A/C Geek I have mine Dialed in dead on.. as a result it was 95 wit ha dewpoint between 72 and 74 the other day.. sunny.. and my bus is factory 1990 insulation, high head room, tall non tinted windows, 7 row .. headed into the sun my driver area was a comfortable 68..

[T-Bolt]

Originally Posted by cadillackid

yeppers sounds like a locked up compressor..

to fix it


1. recover the freon out of the system (requires a refrigerant recovery machineand tanks or have a shop do it).


2. disconnect and remove compressor.. get a clear glass or cup and pour the oil out of the compressor. if the oil is nice and clear and doesnt have bits of metal in it then you are scott free, if its grey or filled with metal the nthe system needs fully flushed. draining oil on a busted compressor is a bit tough as it can be turned.. so rocking it around and pouring oil out of the freon ports and also out of the drain plug hole (if it has one) usually works. save the oil. we will need to know the amount if its clear. also note the inside of the pipes right near the compressor if you stick your finger in and it comes out black and grimy flush the system. if its mostly clean you are golden.



3. obtain a new receiver / dryer. without seeing your existing one (usually on or next to the underbody condenser) i cant say what to get.. they are pretty common and will be a cylinder shaped device 6-8" long. with a freon line coming in and out. blue or black.


4. obtain new compressor. the old one should have a tag of some sort ( I didnt read back through the thread you may have pictured it).. based on that a suitable part number can be found..



5. if the oil is clear and your new compressor ships with an oil charge then drain it into a new cup(if the compressor has a drain plug on the body unscrew it.. slowly rotate the compressor and rock it a bit until it seems most all oil is out.. (you can skip this step if you had to flush the system).


6. calculating the system oil is rather complex unless it is tagged someplace.. many installers Tag the amount of refrigerant and amount of oil required on the bus.. you always hope you can find this tag otherwise its time to get the math book out or find a system similar to yours and add that much oil.. I wont go into the math for it here.. not enough oil and you nuke a new compressor.. too much oil and the thing loses capacity and may liquid slug the compressor.. its not a mission critical thing so you can be off a little and be OK.. but again i didnt re read thread to see the exacts of your system.



back to oiling if you arent flushing the system then pour in the same amount of new oil back to the compressor that you pulled out of the old.. so if you drained 1.5 oz from the old compressor pour 1.5 oz new oil back into the new compressor.


if you flushed your system you leave the factory oil charge in the new compressor.


7. install new compressor and replace the O-rings when doing so.. put on the belt but dont plug the wire in yet.



8. remove the old receiver/ dryerand match it up to your new to make sure the new will fit. pour 1 oz of fresh refrigerant oil into the new receiver / dryer and install it.. use new O-rings. (this step should be completed at the same time your system will be evacuated and charged. the receiver / dryer has a dessicant, the least time it can spend in the air the better.. os I always replace it last and replace it after I have my vacuum pump and gauges connected ready to go).


9. Evacuate the air from the system using an HVAC vacuum pump.. 500 Microns is what I shoot for but 750 or 1000 is fine for an R-134a system.


10. Charge it up. (assuming vaccum holds for 30-60 minutes) I like to weigh-charge in the first portion of the charge. I also like to do this with a high system load.. so a day over 80 in the sun where the bus has hot -soaked.. Ill open all the windows or most of them and the doors so the system stays under load. I start with engine OFF and A/C OFF. I Punch in pure Liquid through the HIGHJ SIDE port for as much as it will take.. this is fast and usually gets a few poounds in. in case its taking lots ill stop at about 1 lb under tagged charge amount. otherwise once scale stops I close my gauge valve.



wait about 2 minutes then I plug the wire in on the compressor, start the engine and set the A/C to Maximum settings.. set the idle speed to 1200-1500 RPM.



I observe the system and will slowly bleed-charge in the rest of the refrigerant.. that last pound I will wacth the site-glass if one exists and also monitor my Superheat. I want to see my Suction pressure Match pretty close the Saturated Temperature.. so I measure evaporator temp at the inlet after the TxV and at the outlet.. a fully charged system will find its temperature at the evaporator midsection matching that of a PT chart pretty close in pressure.. thats the refrigerant temperature inside the pipes will match so its expected that the pipes may be a degree or so warmer than the substance in them... dont measure the air temp.



enjoy your ice cold A/C.


sound complicated? you can always wing it and charge the system till the suction line is cold and hope for the best. or you can send it to a shop.



im giving you the ideals for long lasting ice cold A/C.. then again im an A/C Geek I have mine Dialed in dead on.. as a result it was 95 wit ha dewpoint between 72 and 74 the other day.. sunny.. and my bus is factory 1990 insulation, high head room, tall non tinted windows, 7 row .. headed into the sun my driver area was a comfortable 68..

cadillackid do you work on AC systems? I would gladly drive to you.

[cadillackid]

I work on them when I have time.. did a few this summer, work is busy and now im so far behind on my own projects that im going to struggle to be ready before it gets chilly out.. (as much as I love my nice cold driver seat on 90 degree days I really detest fall / winter weather.. as all I do is shiver whereever I go).. so its game on for me now to do some battery upgrades to the DEV bus and some changes to its heating system.. as well as try and salvage the one Bus-Caravan trip I would desperately like to go on with my Superior (which is still in pieces).. ironically I see your SIG is lafayette.. ive driven near or past lafayette more times than I can count in the last 9 months.. the only road trips Ive managed to take in the last 13 months have been numerous Columbus to chicago trips for work via Bus or pickup..



I cant remember, whats your A/C doing? (or not doing?) time can be had here or there but not in multi-day blocks dedicated..

[A_Bus_Called_Quest]

Originally Posted by cadillackid

yeppers sounds like a locked up compressor..

........

sound complicated? you can always wing it and charge the system till the suction line is cold and hope for the best. or you can send it to a shop.



im giving you the ideals for long lasting ice cold A/C.. then again im an A/C Geek I have mine Dialed in dead on.. as a result it was 95 wit ha dewpoint between 72 and 74 the other day.. sunny.. and my bus is factory 1990 insulation, high head room, tall non tinted windows, 7 row .. headed into the sun my driver area was a comfortable 68..

Cadillackid, you are a real hero - this is amazing.

I'm going to read through it a few times, but my eyes are already crossing and I'm already up against the clock for the build - trying to be out by November 1st.
I'm tied up finishing the build and prepping for move-in / move-out of the house. I doubt I will have time to DIY this fix in time even if I did understand how, so I think this one will go down in the books as an "outside job."

Do you think any Auto / Truck AC shop will be able to do the job? Dare I ask how much you think a job like this costs?

We wont need AC for a few months and I need to get her back into the shop for a final once-over before we leave anyway. . .

[cadillackid]

cost wise - hard to tell.. all depends on whether the easy scenerio (oil is clean so no flush needed) or if its nasty.. flushing can be a tedious long project that often involves many hours and taking things apart.. I cringe when I have to do it.. *USUALLY* Sanden compressors dont send Gray Matter through the pipes.. (fords almost always do). one can Hope that the Bearing or swashplate just seized and thats that.. it will be an easy job..


freon recovery takes about 30 minutes with a nice machine. change the compressor maybe 30-60 minutes..if iits accessible and the bolts spin. allow 90 just to play with the oil measuring from old to new.. Vacuum pump is usually an hour when done right. 30 minutes to charge it maybe 60 if you want to let it run and test air and pressure over time..



flushing? depends on how bad.. I always take the hoses off at the compressor, evaporator, and condenser and flush them separately.. a good strong air compressor us a must... hoses are usually effective at being flushed one way.. evaporator and condenser I flush back and forth a few times.. there are aerosol cans designed for this.. they suck.. you need compressed air and a drilled out blow gun unless its one of the good old ones.. liquid flshing agent is a good way to start.. then I end with alcohol (both in the A/C and a different type in a glass for me once im done flushing an A/C).. alcohol evaporates and tends to help moisture evap too so the last run through is with the alcohol and then lots of air.. you want as much of that stuff out of there as you can get.. doesnt have to be Perfect as the vacuum-down cycle (why micron level is important) gets the rest of the moisture out.. ive blown through the system with my nitrogen if I have some on hand..



after flushing the vac-down cycle might be 90-120 minutes while all the moisture evaporates


sucking things down to extreme vacuum QUICKLY lowers the boiling point of water so it is a vapor and gets sucked out by the vacuum pump..



for A/C geeks out there a standard regular vacuum gauge might read "close to 29 inches of Hg" which is "near perfect right?" wrong.. not for A/C..


at 28.5" the boiling point of water is about 90f
at 29.0" its about 77f
at 29.62" its 45f


wow an inch of vacuum that you might not see on a normal set of HVAC gauges makes a HUGE difference..



at 29.87" its 6f


most vacuum gauges good ones will switch to Microns around 29.80 oir so because its a much better resolution..



your vacuum pump slows down the lower you get.. one its harder to pull that kind of vacuum and two its evaporating liquid moisture which makes it a gas which means it expands and adds pressure.. something more to be sucked out by a pump already working hard.. thus why I stress the importance of a 500 micron vacuum as it gets out pretty much all the water and most anything else that boils within that range...


I typically start up my vacuum pump and then go about my day and check on it periodically...

[A_Bus_Called_Quest]

@Cadillackid -

No wonder you don't have time for your own projects, you're too busy on here helping us out!

When you say flush, you're talking about the AC compressor, lines and designated radiator in the back unit, right? (Not the engine?)
Can any of this effect engine performance in the meantime if I leave the bad compressor unplugged until I can get it fixed?

[Kubla]

It will not hurt anything to leave the compressor there, you really should to keep the system sealed until you are ready to fix it

[cadillackid]

What kubla said.

Flushing - lines condenser evaporator .. Never flush a compressor (it’s bad anyway you are going to trash it ). Never flush the TxV valve. Always remove it from the evaporator before flushing .

As for my time on here a lot of it is when I’m sitting on hold on conf calls or waiting for people to complete tasks .. Ie worthless IT newbies who can’t even configure a VLAN to save themselves

[A_Bus_Called_Quest]

I definitely am adding this to the list of "outside jobs" - I'll call around to a few AC mechanics in-town to see if they'll take the job.

Crazy left field question here - since I'm getting cold on one side of the AC, is there any sane reason or way to delete the malfunctioning half? It would free up some head room in the bed room . . . and the way the bedroom wall is built, the functioning half of the AC is blowing straight through the hallway, into the living space, whereas the disabled side is blowing only in the bedroom / onto the bedroom wall.

Am I crazy?

[cadillackid]

I dont know how those coils are built, butthe easiest way would be to disassemble the whole thing and put a small evaporator up on the ceiling or a custom solution of some sort.. you could then delete one compressor and one condenser (I think you said you have 2).. you'd lose half the cooling capacity but if you are super insulating your bus you have half a chance of staying cool upfront with one.. ie removing the interior to the bones spray foaming and rebuilding and RV windows or skoolie windows if you are deleting a good many.. but if you are planning on stock insulation you'll want both systems functional.

[A_Bus_Called_Quest]

Originally Posted by cadillackid

I dont know how those coils are built, butthe easiest way would be to disassemble the whole thing and put a small evaporator up on the ceiling or a custom solution of some sort.. you could then delete one compressor and one condenser (I think you said you have 2).. you'd lose half the cooling capacity but if you are super insulating your bus you have half a chance of staying cool upfront with one.. ie removing the interior to the bones spray foaming and rebuilding and RV windows or skoolie windows if you are deleting a good many.. but if you are planning on stock insulation you'll want both systems functional.

Evaporator! that's what I've been calling a radiator, lol
Everything seems pretty hardcore mounted to the ceiling, and the unit uses 3x blowers, with 2x vents on each blower - so that would be the odd part of a 1/2 unit delete - using 2x blowers (4x vents) on the 1 evaporator.
I suppose I would then have to re-fab the AC housing as well . . . probably better/easier to just repair it and enjoy the added chill.


As for STAYING cold, once we get there - I did a full demo, spray foam walls and ceiling, with plywood walls and 1x4 ceiling.
I've "deleted" almost all of the window lowers with white vinyl on the glass, 1.5" XPS foam and 1/4" plywood interior wall, leaving only the top half that actually opens.

We may add a rooftop AC sometime down the line, powered by a generator - this seems like the easiest after-build installation (vs. mini-split).

We're planning to chase that sweet 70° - 80° weather, so hopefully AC doesn't become a life or death issue - but we do want to be prepared for anything

I'm definitely buying you a beer, or dinner, or whatever you consume if we're ever out in OH - you really have been an amazing help

[cadillackid]

Ha! In the AC world it seems humanly backward. The condenser is the outdoor part. The evaporator is the indoor part.. weird since the evaporator condenses moisture. Reality is the Freon condenses in the condesnser and evaporates in the evaporator..

Why not delete the rear unit altogether and put a smaller unit inside the header panel above the driver seat. Since you are insulated well this will do a good job keeping driver and passengers cool. A bulkhead unit is what I’m thinking of. They only protrude a couple inches into the cab vs hang down.

Then you’d delete one compressor and one outdoor unit. Move the rest to the front where the people ride. Rooftop unit could be 2/3 way back for use when parked or if you really neeeded it as a boost on genny while driving

[A_Bus_Called_Quest]

Originally Posted by cadillackid

Ha! In the AC world it seems humanly backward. The condenser is the outdoor part. The evaporator is the indoor part.. weird since the evaporator condenses moisture. Reality is the Freon condenses in the condesnser and evaporates in the evaporator..

Why not delete the rear unit altogether and put a smaller unit inside the header panel above the driver seat. Since you are insulated well this will do a good job keeping driver and passengers cool. A bulkhead unit is what I’m thinking of. They only protrude a couple inches into the cab vs hang down.

Then you’d delete one compressor and one outdoor unit. Move the rest to the front where the people ride. Rooftop unit could be 2/3 way back for use when parked or if you really neeeded it as a boost on genny while driving

I think this is how we will end up eventually. . . I've left everything accessible on the old unit, just incase we need to service - or remove!

I love the idea of splitting the unit, keeping the smaller side up front somewhere to cool us while driving.
There is also an empty section of ceiling just calling out for a rooftop AC -i was looking at some of the Dometic RV AC units and they look just about as easy to install as thr MaxxFan.

Going to read up on capturing / refilling that freon, as it is the only part I'm not sure I can handle right now with the tools on hand - everything else seems fairly mechanical and straight forward. I this old bus - so easy to work on!

[Bouysou]

Looks great Meathead!

[JenniferWillow]

Yesterday I had scheduled with a mechanic to remove the freon from the rear air conditioner so we could remove it. When I met the mechanic we even struck a deal where he would remove the AC system for free and he'd get to keep the AC. I was ready to turn it over to him for the work but I thought we should at least try to turn the system on first.
I had assumed that the AC wasn't working or at least wasn't working well. I was wrong. The rear AC worked great and would keep the bus as cool as you'd ever wish. The plan changed. We spent an hour talking about relocating the system to under the bus. I even got a bunch of aluminum extrusion to build a box that would hold it.
After really looking at the system over this weekend we have decided to keep it. After removing the cowl the system is MUCH smaller and I can custom build shelves around it and make a beautiful cover for it.

[cadillackid]

Originally Posted by JenniferWillow

Yesterday I had scheduled with a mechanic to remove the freon from the rear air conditioner so we could remove it. When I met the mechanic we even struck a deal where he would remove the AC system for free and he'd get to keep the AC. I was ready to turn it over to him for the work but I thought we should at least try to turn the system on first.
I had assumed that the AC wasn't working or at least wasn't working well. I was wrong. The rear AC worked great and would keep the bus as cool as you'd ever wish. The plan changed. We spent an hour talking about relocating the system to under the bus. I even got a bunch of aluminum extrusion to build a box that would hold it.
After really looking at the system over this weekend we have decided to keep it. After removing the cowl the system is MUCH smaller and I can custom build shelves around it and make a beautiful cover for it.

if the plastic cover on yours had the drain hoses directly connected to it then that is also the drain pan, be sure to incorporate a drain pan as part of your new cabinetry around it.. if the inside unit has a drain pan still there after removing the shroud then you are good..



alot of people relocate the inside unit to the front.. or if they have 2 systems they pull the rear and keep the front.. theres lots of options.. I have built quite a few custom setups.. in my old superior bus i found a super powered unit that fits under-the dashboard and keeps the front part of the bus ice cold even in really hot weather.. (looks like vintage like it came with the bus)..