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Andy, Truck Diagnostic Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 1675
Experience:  International and Isuzu trucks , International, Maxxforce, Cummins and Isuzu engines, Diagnostic and electrical troubleshooting specialist , Hvac and truck /trailer refrigeration troubleshooter
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Peterbilt387, yr 2007. air conditioner problems. air vent is

Customer Question

peterbilt387, yr 2007. air conditioner problems. air vent is not cool as it should. evaporator coil freeze, compressor not recycling
Submitted: 4 months ago.
Category: Medium and Heavy Trucks
Expert:  ][\][iCk0411 replied 4 months ago.

Hi and welcome to Just Answer! My name is ***** ***** I can help you today. I believe the evaporator is freezing because the vent drain for your HVAC system is plugged. Your going to want to locate the drain for your a/c which should be in the passenger side under the unit. Your going to want to remove the cab hepa filter and backwash the evaporator and get it all draining out of that A/c drain. The only other factor that can cause it to freeze is the dirt in the evaporator so wash it out well.

If that doesn't work still then change the Freeze switch which is located beside the evaporator. There will be a small probe that goes into the evaporator from the freeze switch.

Let me know if you have any further questions. Otherwise, I appreciate a rating of my services.

Once your satisfied please accept the Answer and rate.


Customer: replied 4 months ago.
i did them, front and back, thermostat, clean, flush the whole system before i change new parts. Please read the explainations, or call me dean(###) ###-#### i am driving to shipper to pick up load, please call thx
Customer: replied 4 months ago.
Please get a call
Customer: replied 4 months ago.
Pleae read my truck a/c history. I bought this truck (Peterbilt 387, yr 2007 )on sept/2012. Engine is cat , acert c15 twin turbo .A/c was working fine, but i notice air compressor clutch never cycle, I thought that the way it is, and vent air come out from 38f to 42f. After one yr ( 8/2013) i drove then air compressor got burn. I took to shop n mechanic flush whole system, then he changed new a/c compressor, condensor, air drier, front expansion valve, then vac, recharged 3.8lbs r134, after that the a/c is not cold as it should, and a month later a/c works intermittently, I personally troubleshooting, I changed thermostat, low n high pressure sensor, clean front duct filter. And a/c is not cold as it should. But I didn't have time to repair till this yr. I would like to complete repair a/c system. I brought this to the professional a/c shop, mech change almost everything new ( he changed: air compressor, condensor, air drier, two expansion valves, thermostat, two a/c hoses on front,( low n high ) , two actual temperature blend doors, clean all drain hose , change evaporator filters front n back) then vac, recharged 3.8 lbs r134, . Now a/c is still not cold, vent air out from 55degree to 65 degree, n evaporator coils get freeze on front n back. If you need more details please get me a call. My truck has two unit but works under one compressor. The front unit works like car, but the back ( sleeperbert) a/c work by climate control system. I did spent almost 2000.00 and a lot of time, but a/c still not properly. If you live or know any professional a/c mechanic or shop nearby Los Angeles, ca please let me know. I don't tell me goto Peterbilt dealer, i don't trust these guys
Expert:  Andy replied 4 months ago.

Hi there . My name is ***** ***** In a case like this , what I recommend my customers is installing a shutoff valve into the heater line to completely stop the flow of coolant through the core therefore , absolutely no heat going to the core at all which usually helps to cool the inside of the cab significantly greater . That and a clean or new hvac filter to assure maximum air flow accross the evaporator core to prevent freezing or icing of the core

Customer: replied 4 months ago.
i did closed two valves heater core on front but still not cool n my rig has four valves heater core, 2 on front n 2 on back.
But now i let all four valves open due to weather change, because day in arizona very hot then night some where in colorado is cold, so i need a/c on day n heater on nite without stopping
Customer: replied 4 months ago.
Without stop driving
Expert:  Andy replied 4 months ago.

ok what about hvac filters inside and out . Are they new or very clean to allow lots of air flow through core to prevent icing up?

Customer: replied 4 months ago.
my question is, is my Peterbilt 387, yr 2007, a/c compressor runs constantly, no cycling or have to stop then runs again???
Customer: replied 4 months ago.
My a/compressor clutch runs none stop, why???
Customer: replied 4 months ago.
Can i call you or you can call me dean(###) ###-####
Expert:  Andy replied 4 months ago.

Good luck with your AC . I hope a good Peterbuilt technician figures it out for you .

Customer: replied 4 months ago.
Thx andy. Maybe i am lucky to catch a good guy.