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Old 08-21-2017, 05:44 PM   #1
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Rear AC help

Hey all, I have a 95 Short Bus with rear air. I need help figuring out how to get it working. Heres what I did so for:

1. Added 2 small cans of AC dye (red). Compressor under hood DOES come on. I searched everywhere...no leaks (dye) found anywhere.

2. Hooked up nitrogen bottle, pressurized to 150psi. Let it sit for over an hour...stayed at that pressure.

3. Removed nitro....took freon can off gauge, pulled trigger to release pressure. Added 1 can of 134A and held at 25 psi. I have NO cold air from either rear unit nor front. I did find that compressor only comes on when turning on rear ac fan...NOT front dash fan.

Any help would be appreciated. Thanks
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Old 08-21-2017, 05:46 PM   #2
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when you remove the nitrogen did you pull a vacuum in the system

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Old 08-21-2017, 11:57 PM   #3
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First evacuate the system, next you will need up to 4 lbs of r134, the pressures should be around 30 lb low side, 150 high side with a c on. the condenser fans or engine fan depending on the system should be on. If still not cooling, you have other issues.
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Old 08-22-2017, 09:12 AM   #4
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No, did NOT pull a vacuum. Is that necessary before adding Freon?
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Old 08-22-2017, 09:14 AM   #5
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Did not evacuate the system. (I take it that means pulling a vacuum?)
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Old 08-22-2017, 11:10 AM   #6
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First, the system needs to be evacuated, the nitrogen you added won't compress. Second if you vented the nitrogen and allowed air in the system, it needs to be evacuated and a vacuum pulled to get any moisture out. The vacuum will then pull the refrigerant in. The next step is to connect the refrigerant and let the vacuum pull in as much as possible. Then run the system and add as necessary (I don't know the pressure of that system)


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Old 08-22-2017, 11:12 AM   #7
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If the compressor doesn't turn on, it probably has a low pressure cut off that will have to be bypassed in order to charge it the rest of the way. You need the compressor to pull in the refrigerant and pressurize the system.

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Old 08-22-2017, 12:00 PM   #8
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MOST SURELY evacuate!! im an A/C guy and I cant stress enough how non condensables (Moisture, Dye (yes even tracer dye in too much quantity can be detrimental), Oil (too much oil will make a system not cool well), Nitrogen, AIR). all will greatly impact (negatively) system performance..

you MAY be able to rent an A/C vacuum pump from an auto parts store. or perhaps a place like Sunbelt rentals. being its summer and moist outside the vacuum pump should run a minimum of an hour on a system like that... if it has been opened up long, id vacuum 2 hours.. your system will have a receiver / dryer. and that has a dessicant in it. which. takes a whilke to get the moisture out of.. moisture is opulled in the presence of a vacuum..

once vacuumed you should be able to punch at least a pound into the system. before you turn it on... punch that first can in Upside down. with the A/C OFF!!!.. this gets the most liquid in ..

now see what your standing pressure is... it should be up there at 60 or above once the refrigerant settles and evaporates... (in a system that size) unless its pretty cool outside...

after a few minutes, now start the van and turn on the A/C. you should see your gauge pressure drop on the low side. typically the low pressure switches are set low enough you can get the compressor to start.. or if they are using the factory system switches, it will kick in and out in and out..

** 25 PSI standing pressure may NOT bde enough to fire a low pressure switch thats been located on the high side. **. as mentioned you may need to find it and put a temporary jumper across the harness to get the system to run..

once you get the compressor running. put in the rest of the refrigerant as a gas.. meaning cans right-side up... the cans will get cold.. I typically have a pitcher of warm water to dip the can in to warm it up.. refrigerant will not flow from a frosty can.

hope this helps a little..

LOVE the red bus!! looks like the little brother to mine!!
3AE5860F-3D6F-4E82-B07C-559F916F5A8F.jpg

I just evac'd and recharged the A/C on mine.. took out over 8 ounces of non-condensables... and its STILL a bit over-oiled.. but not bad

-Christopher
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Old 08-22-2017, 03:09 PM   #9
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CC, would you come out here and recharge Brunhilde for me?
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Old 08-22-2017, 06:16 PM   #10
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You rock!!!. Going to borrow a vacuum. Will keep y'all posted
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