Air Conditioning Problems, Please Help!

97classic · #1 (**permalink**) 07-25-2008, 02:09 PM

Hey there everyone, I am new as you can tell! Here is my problem, when i bought my truck the ac worked great but would go out after a bit, then later , and i mean later it would come back cold as everything, so i changed out the breaker and seen the bunk blower wouldn't work, so i pulled the switch and it was burned, so i replaced that,but since I have cleaned the ac unit ie blower in the front and rear! So i have been running it a bit and the ac hasn't failed yet, as far as the ac in the front! My problem is this, the ac is the front working great now i guess lol. And the ac in the bunk is blowing warm air, I dont know what is going on, I mean the ac from the rear is joined with the ac in the front, seems it should be cold but it isn't! Also the bunk air makes a hissing noise from the vent and i can hear it under the bunk! Can someone help please? Sorry, the truck is a 97 freightliner classic!

mechanix · #2 (**permalink**) 07-26-2008, 12:37 AM

First off,for quicker replies try posting such questions in the wrench benders section.
sound like you fixed the first problem dirty evaporator causing it to ice up and quit moving air.
The second( and I'm not totally sure on frieghtliners),some trucks use air to control the duct doors,you could have loose hose or a bad acuator. thus causing the door for the a/c side not to open... Find the source of the sound and you will most likely find the porblem.

97classic · #3 (**permalink**) 07-26-2008, 12:57 AM

Well thanks, I didn't see a tech side thanks! How do I check the actuator? Also I noticed there is no water dripping from the bunk and the lines under the cab don't get hott or cold!

ranger309 · #4 (**permalink**) 07-26-2008, 10:38 AM

Quote:

Originally Posted by 97classic

Well thanks, I didn't see a tech side thanks! How do I check the actuator? Also I noticed there is no water dripping from the bunk and the lines under the cab don't get hott or cold!

I could DX your AC system, as I have converted a few non-AC cars to AC on the side, but if your cab A/C is working A-OK there must be some valve, switch or door that is not working properly because the A/C all works off of the one A/C compressor mounted on the motor.

ranger309 · #5 (**permalink**) 07-26-2008, 12:42 PM

Quote:

Originally Posted by 97classic

Well thanks, I didn't see a tech side thanks! How do I check the actuator? Also I noticed there is no water dripping from the bunk and the lines under the cab don't get hott or cold!

There is your Dx right there. If the lines for the A/C are at ambient temp
its no wonder the A/C isn't getting back to the sleeper. When dealing with A/C, the larger lines should be cool to cold and even sweating with atmospheric water condensation, while the high-side should be warm to hot.

Your drip lines should be dripping with condensation water if the system is working properly. If not you have a problem of some sort. Probably a switching issue of some sort, that isn't allowing the refrigerant to flow to the sleeper cab evaporator.

HiwayHombre · #6 (**permalink**) 07-26-2008, 12:52 PM

Quote:

Originally Posted by 97classic

Well thanks, I didn't see a tech side thanks! How do I check the actuator? Also I noticed there is no water dripping from the bunk and the lines under the cab don't get hott or cold!

You say that the front unit cools fine, is that right? Is the suction (big) hose cold at the compressor? Is your front unit evaporator freezing up?
Since the bunk evaporator core is the fartherest flow component away from the compressor and the suction hose isn't cold, it may just need a shot of gas (134A of course). If you know how to add gas, give it one can and see if you get flow to the bunk unit. If you've never done it, you may want to find someone that's fluent in charging a/c's and let them do it... It sounds like a flow problem. You may want to gauge the system for flow pressure right off to save a bunch of guess work...