97' Freightliner Century weird A/C Problems

[turbodave]

Hey drivers, I have a 97' Century condo and have a couple of problems with my A/C that maybe some of you have experienced.

First, the rear A/C blows warm air and the lines from the junction of the front evaporator are don't get cold. I have some ideas but would like input.

Second: When driving down the road w/ A/C on recirc., the A/C system except for the blower will shut off and blow warm air when I start to slow down and won't come back on until I leave the system off for a while. The computer won't kick the radiator fan on either. When the system is on fresh air mode, it works fine, no problems (except the rear A/C).

This second problem I know will cost me few dollars to have someone diagnose and I don't want to get ripped off by a repair shop for diag time.

[Windwalker]

I could be wrong, but it sort of sounds like it's one of the sensors that turns the fan on. If the freon temp in the heat exchanger builds up enough, the fan should come on to cool it off. If it does not, the compressor will not come on, no freon will pass through the system, and you get no cooling. When you're moving down the road, the air is "forced" through by your speed through the air. When you slow down, you lose this effect and the fan must take over. If it does not, you get no cooling.

When going on the hiway, my fan only kicks in when pulling a hill. When I slow down for city speed limits, the fan kicks on and off to cool the AC.

[turbodave]

You could be correct but it happens when I let off the gas like I am going to slow for a scale house from highway speeds or exit ramp. The fan does kick on and off when the system is working but when it shuts off it only works when the engine temp reaches a certain temp. Its like somebody shuts the a/c. I think this is going to be a tough one.

[Mr. Bighead]

It's pretty likely that both of your problems are caused by low charge. You can still have enough freon to make the system work, but not enough to work right. It sounds like your system is freezing up. I've seen a lot of century classes freeze up when the system gets a little low. If it's low enough, it won't have enough liquid freon in the system to make it all the way back to the bunk, so the a/c in the bunk doesn't work at all.

The most common slow leak is the front seal in the compressor. Look and see if you've got dirt built up behind the pulley. The leak really could be anywhere in the system, though. Until recently, century classes had a poorly designed condenser that was bad about leaking. Just check all the lines and see if you can find oil on them.

If the system hasn't been worked on in a long time, it might not even be worth the trouble of finding the leak. If you get it charged up, it might work fine for a few years until it gets low again. If it was mine, I'd take it to a shop and have them recover the freon to see how low it is. If it really is low, then you have to decide if it's worth trying to find and fix the leak.

[turbodave]

Thanks bighead, thats the type of information I was looking for. I know these things have certain problems or quirks that are common just like certain cars have certain common problems. Since I am new to this, I just starting to learn about these big trucks. I ve learned a lot in the three weeks I ve owned it and realized its not much different than cars.

I'll probably evac and recharge the system from scratch.

Thanks!