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Joshua Haynes
Joshua Haynes,
Category: Chevy
Satisfied Customers: 276
Experience:  Lead Technician/ Manager at Precision Tune Auto Care
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Rear air conditioning air handler is not blowing cold air.

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Rear air conditioning air handler is not blowing cold air.
Customer: replied 1 year ago.
The van has forward and rear air handlers, and the front a/c blows cold, but the rear a/c does not. The van is charged with the hard-to-find r-12. 3 years ago I had the compressor re-built with new seals, new hoses to the rear air handler and a new expansion valve fitted. Then whole system was charged with r-12. I think the rear heat is stuck on, therefore counteracting the cool air, but I dont want to overlook other A/C system components that could be near failing. For example, if the compressor is failing and bits are clogging the rear expansion valve, I want to know!

Hi, my name is ***** ***** I will assist you. Unfortunately, the only way to know if the rear expansion valve is clogged is to check the valve visually. the rear system has no pressure ports and is annexed off from the rest of the system so you cannot monitor rear-specific pressures. To do this, as I'm sure you know, you would need to evacuate the system and then pull off the part (which is easier said than done with r12!). I would suggest ruling out the blend door operation first by changing the temperature from hot to cold in the rear and checking for any change at all...of course you won't feel COLD air, but if the blend door is working and the a/c is not then the temperature should at least change some. Let me know how this goes!

Customer: replied 1 year ago.
thanks for the response. I think we have some pretty conclusive results. I used a IR thermometer to read the forward and rear air handler outputs. Before starting the engine, but letting the blowers run, I read 93 front and 92.3 in the rear. After starting the engine, with no A/c on, just vent, and mixer at cold, after 8 minutes of idle, the temps were 96.8 front and 113.0 rear. Then I turned the heat mixer toward hot (about half way) and after 5 minutes, the temps were 127 front, 127 rear. Then I turned the heat off and a/c on, and after 5 minutes, the temps were 56.7 front and 80 rear. So it seems that each time, the rear is consistenly hotter than the front, and when the heat was on, the two temps aligned equally.

Ok, so it sounds like the blend door is moving in the rear, but the a/c is not working in the rear. I would suspect either a stopped up rear expansion valve or clogged evaporator. Good luck!

Also, please don't forget to leave a positive rating if you were pleased with my service. Thanks!

Customer: replied 1 year ago.
I was thinking just the opposite. When there should be no heat, the rear air handler was pumping out air about 20 degrees above ambient and 15 degrees above the forward air. And when the air con was turned on, the rear air temp dropped to about 13 degrees below the ambient initial temperature. If the rear heat control worked, the rear air vent would be at nearly ambient. And when the heat was turned up, the forward air handler jumped 30 degrees while the rear only increased 14 degrees.
Customer: replied 1 year ago.
I think the heater control in the back is broken and dumping heat into the air, over powering the air conditioning. I dont care about heat, so can I simply find the two tubes carrying coolant, to the rear, and use cut them, and use a simple male/male hose connection to connect them together?
Customer: replied 1 year ago.
I live in Miami so I dont really care about heat. Will bypassing the rear heat exchanger be bad?

I read that info differently...I didn't realize it was that far above ambient. In that case, I would try this first before you do anything else: go under the van to the rear evaporator lines where they go into the cab (should be right rear) and feel that one is getting cold and the other is staying hot. This will help determine if the a/c is working properly and you just have a blend door problem or if the a/c is inop. If they are cold and hot respectively, then you should have no problem at all diverting the air permanently over the evaporator in the rear.

Customer: replied 1 year ago.
two are slightly cool, two are hot. Will a regular bronze male/male coupler, double hose clamped, be ok for that repair? And assuming that this fixes things, going forward, what are tell tale signs of a compressor going bad? Sounds, squeeks, leaks, ?? thank you!!

two of the lines are for the heater core in the rear, and should be hot. The other two should have one cold and one hot if the a/c is working. It sounds like your rear a/c may not be working. But, to answer your question, I need to know what repair you are talking you mean locking the blend door in the cool position?

Customer: replied 1 year ago.
I didnt think there was actually a door. as far as I can tell, there is no control into the rear air handler for a door. There are simply 4 hoses, and a wire for the blower motors. I think there is just a cooling evaporator, and a heater radiator. I think there is a valve in the front of the van, to which a cable pulls open and closed, to adjust the heating in the rear. I was wondering, if instead of trying to locate and fix that valve, I could just remove heating from the rear basically, and splice the heater hoses together, thereby bypassing the rear heater entirely. I just dont want to hurt anything up front by doing that.

Ok, so you are talking about looping the heater hoses in the rear together and bypassing the heater core all together...I'm on the same page now. No, that would not be a problem at all, provided it does not leak.

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