Having trouble with E450 A/C system. HELP needed.

[srponies]

Are there any automotive A/C gurus out there? I just assembled the main A/C on my 2001 E450 shuttle and it's not functioning properly with a recharge.

I had removed the aux/rear a/c blower/evap/condenser/fans/hoses. It had been Tee'd into the front hoses with special aluminum tubes. I Didn't flush the front evap, compressor or hoses. I installed a new front condenser, accumulator, orifice tube, low pressure switch. Vacuumed system(held vac for 30 minutes), added oil, added approx 44oz 134A. Compressor clutch kicks on at 44ps and spins for 10-15 seconds. Low pressure drops very quickly from 44psi to 25psi. Compressor shuts off. Low side pressure rises VERY slowly (2-4 minutes) back to 44. Then repeats. High side goes up from 150 to 200 ps when compressor runs. It is 80 deg out. No cold or sweating A/C hoses. No cool or cold interior air. A/C sticker underhood says that system without rear a/c holds 2lbs, 12oz. That's what I was trying for.

Any ideas for me. Thanks.

 

[cadillackid]

sounds like your orifice tube clogged right up dfrom leftover dirt in the system or the components you sourced.. id reclaim it, pull the orifice and check it.
-Christopher

 

[srponies]

It looks pretty clean to me. It was installed with the shorter end into the line going into the evaporator. It appears clean enough to reinstall. I just disconnected both lines at the evaporator and blew it out a bit with compressed air. Lots of oil in there.

Steve.

 

[cadillackid]

how much oil did you put in the system? you probably only need 8 oz of oil total in just the dash air.. and did the original system have a TxV in it somewhere that got missed and so you are trying to operate with 2 metering devices?
-Christopher

 

[srponies]

I added 5-6 oz oil when I reassembled. Poured a few in the condenser, a couple in accumulator, and added 1 when charging. I used PAG46. I don't believe this system has/had expansion valve. I removed what appeared to be an original orifice tube from the evap inlet tube when I had the hoses disassembled to remove the rear system.

Steve

 

[srponies]

Some more information. Yesterday after I had charged the system I left the engine run/idle for an hour or so. The high side pressure kept creeping higher and higher. It made it up to the 325-350ps range. Low side stayed between 20 and 50 or so.

 

[cadillackid]

is the condensor or the liquid line from it getting hot? this seems like no heat being moved from the condensor or a grossly over-charged system.. a blocked orifice usually wont make the head pressure go up like that.. in fact the head pressure will go low if you had a blockage.. something just seems off here..

 

[srponies]

I just started over with vacuuming the system. Then I turned on A/C and bypassed the low pressure switch to get the compressor spinning. I charged with (1) 12oz can. While charging, the can, sight glass, low side manifold and hose began to freeze up. The low side pressure increased to about 10, then dropped into the vacuum side. High side pressure is at 60.

I'm not sure how to best test for a blockage within the components besides taking it all apart and blowing through everything. Also, how can I determine if there's an internal compressor problem?

Thanks for the help.
Steve

 

[srponies]

I just found a post with a similar situation as mine.

http://http://www.autoacforum.com/messageview.cfm?catid=2&threadid=14482

 

[cadillackid]

the site glass started to freeze? where is the site glass in the system? it should be after the condensor and before the orifice tube..

freezing after the orifice tube and before the evaporator is normal and expected on a low-charged system..
-Christopher

 

[srponies]

Site glass on my gauge set. The entire track from the can to the low side port on the accumulator was freezing.

 

[srponies]

I ordered a replacement compressor. I am going to disassemble the system, flush the evaporator and the lines to the compressor. Then install the new compressor and new orifice tube.

Don't know if the accumulator and condenser (just replaced) would have been spoiled or plugged already. I will probably blow thru them with compressed air, but not remove or flush them.

Steve

 

[cadillackid]

if the compressor is wrecked, replace tjhe accumulator, flush the condensor.. the accumulator usually has a filter in it.
-Christopher

 

[srponies]

I am replacing the compressor because at this point I don't know what else is causing the pressure issues, and I want to be able to trust it long term. The accumulator and condenser are new (but have been used when trying to get this system to work). Are you saying that I should replace the accumulator again (it is a royal pain to remove and will have to remove battery and many cables again to gain access)?

Steve

 

[raulaleman84]

if the compressor is wrecked, replace tjhe accumulator, flush the condensor.. the accumulator usually has a filter in it.
-Christopher

christopher,
what is a rough estimate on replacing the AC system with a new one on those cutaway buses?

 

[srponies]

Oricha -
Are you talking about the main/front A/C? Doing it yourself?

On my '01 E450 shuttle I have spent the following to get the front A/C going:
Compressor $140
Condenser $ 86
Accumulator $ 40
Hose $ 40
Orifice tube $ 3
PAG oil $ 8
134A Refrig $ 40

Time 3-4 hrs for installation, troubleshooting, evac & recharge.

Hope that helps,
Steve

 

[srponies]

I FOUND THE PROBLEM! I finally had a chance to work on this system some more and found the problem. There was a blockage in the hose between the condenser and evaporator. Not dirt/debris, but (I believe) a manufacturing quality control issue - a rubber plug stuck within the hose section. I just ordered a replacement part and will definitely test/blow thru this hose before installation. Photos attached.

Thanks for all of the help and suggestions.
Steve