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OTR ac mx
On our way home a couple of weeks ago, the OTR air started short cycling, red light on dash. not good. At home I put my gauges on it. I saw that the low pressure safety switch was opening the compressor clutch circuit at about 16 psi. It’s suppoose to do this, but it’s NOT suppose to get down that low. Something was wrong? I opened the condensor bay door and the balls in both the bottom and top accumulator sight glasses were at the top(not good). A restriction causing the liquid freon to fill the accumulator. There is only suppose to be enough liquid freon in the accumulator to float the ball midway up the bottom sight glass. I looked downstream at the forward wall where the drier/filter is located and noticed it was getting frosty about half way thru it. AH HAH !!! I found the restriction. Who knows how long that/filter has been in place? The bus is 24 yrs old? I had a new drier/filter on hand.
I have skills, BUT, I can’t:
1) recover 24 Lbs of R134a freon. I don’t own a recovery pump or tank.
2) braze out the old drier/filter and braze in the new one. I don’t braze.
While discussing the above situation at a coffee shop with a friend, in walked a HVAC guy that my friend had used many times before. After a lenghty interview, I decided to give him a try.
Over the course of a week and 3 visits to my house later, it appears he/we got er done.
We decided to 1) recover all the old R134a freon and take it to a recycler; 2) we leak checked the system for 48 hrs w/nitrogen(no leaks); 3) remove the old POE compressor oil(see pic) and replenish w/new; 4) refill the system w/NEW R134a freon.
We have several 500 mile weekend trips planned in the near future. So we’ll see?
For curiousity sake, I cut open the old drier/filter. YUK!!! but no big pieces(see pics)
Happy Travels – Don -
7 Replies
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Don, where did you get the replacement filter/drier? I asked Prevost Mira Loma to replace mine when they replaced a leaking king valve a couple of years ago but they could not get the right part and probably had no way to braze it in.
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Ebay in 2014 for $26. I’ve had it sitting on my shelf, just in case. I just ordered another, $30, just in case.
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Good catch. As I was reading the post my brain was saying expansion valve and if that was the case I would have replaced the dryer, but you found the true problem.
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Can’t believe you had to solder one in. My older coach 1991 XL had a screw on dryer. Welch Industries, 770-474-1150 has all you need to fix. Google um.
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This afternoon I took the beast out for a cruise so as to test the OTR ac. I’m happy to report all went well. Blows 45 degree air out both the main and dash circuits.
We got the oil level just about perfect(see pic).
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I am in the middle of trying to get my 02 Liberty properly charged . I have not identified a leak yet but it may be time to do what you did and go thru the system and change the oil and nitrogen test. I live in Crosby TX do you think your guy would be up to help me with it. I have an air conditioned shop and every tool known to man. I’ve been all over these buses but never had to do the Prevost OTR .
Wilton Owens
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No, he’s a local guy(N. San Antonio/Bulverde) and is busy, busy, busy. If you were here he would probably say yes.
Sorry for the late reply Milton, I’ve been traveling and offline.
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