Psyco A/C

[tdelorme]

We headed out in the heat last week for a short business trip. After a few miles it was obvious that the over the road air was not working properly. Since we're only going a hundred miles or so, I tell Jan that I will check on the problem when we get home. When we do head home Friday evening, it's still hot so I turn the OTR air on for whatever small amount of relief it might offer. After about five miles I think to myself, "it's getting cold in here." And then Jan says, "turn the fan down." The OTR air is working like a champ. I had double checked the controls on the trip up and had even turned the system off and on a couple of times. Any thoughts on what's going on here?

[jack14r]

I think that the Carrier compressor has a electric clutch that could be intermittent.If it fails again you could open the engine doors and verify if it is rotating.I always like to turn my AC on at the lowest RPM thinking that it is easier on the compressor and clutch.

[Jon Wehrenberg]

Jack is correct relative to the clutch. Also I think there is a box at the top of the first bay, driver side that in addition to the big CB for the system there are some 8 pin base relays. If they get dirty points that may also create an intermittent condition. Unfortunately trying to trouble shoot an intermittent system when it is working is a waste of time.

There are a lot of potential failure points in the system so it would not hurt to poke around looking for potential issues. The evaporator and condenser motors have carbon brushes which are a replacement item. I think I wrote an article that is on the POG site about changing the brushes when they reach the minimum length. An intermittent evaporator or condenser motor will also cause the system to malfunction, although a failed condenser motor is displayed with a lit AC light.

I assume you see freon flow through the sight glass in the receiver tank? I doubt that is the problem however because the system will not refill itself between uses.

[tdelorme]

Thanks, Jack and Jon. If the otr air fails again I'll check things out starting with the clutch.

Jon your comment about the system not refilling itself reminded me of a funny story. My father had an engineer working for him back in the 50's that bought a new VW bug. This guy was bragging about what great mileage he was getting with the VW. My dad and another fellow got a key to the guys car and started adding a quart of gas to his tank every day for a few days. The guy was just really going on about his bug. Then they upped it to half a gallon for a few days and his big talk went crazy. After listening to the talk for a couple of weeks, they started pulling gas out of his tank. A quart for a few days then slowly they upped it to a gallon or more every day. The guy just shut up. The other engineers would ask him about his mileage, but he never could just admit that the VW was only getting about 10 miles a gallon. They pulled the poor guys chain for months before he caught them stealing his gas one day. My dad said he had never been called so many different names in such a short time, but the guy got over it and they laughed about it for years.

[Joe Cannarozzi]

That is downright evil.

[garyde]

Hi Ted. I thought my OTR was acting up on several occasions as well but I could never find anything wrong. It would cycle off. I believe it was the temperature guage.