suction line frosting up

jyesluga on Fri December 10, 2010 4:23 PM

Year: 2010
Make: Chevrolet
Model: Impala
Engine Size: 3.5L V6
Refrigerant Type: R134a
Ambient Temp: 65
Country of Origin: United States

Hi,
I have a 2010 Chevy Impala that, ever since I bought it, the suction line freezes up from the firewall all the way to the compressor. When this happens, there is barely any airflow to the vents inside the vehicle. I have taken it to 2 dealers, and they have done anything from replacing the blower control module to telling me the way the a/c is operating is normal. Is this normal, or is it possible that the system is under/overcharged? Please help!!!!

Thanks!!

GM Tech on Fri December 10, 2010 10:42 PM

Classic freeze-up condition- your variable stroke compressor has a bad control valve- or there is air in the system from and inadequate vacuum before charge- if you lose air flow, the evap is frozen and that is not good-- tell that to your dealer....

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

jyesluga on Tue December 14, 2010 1:17 PM

I was told by the technician that the system is overcharged, or there is a restriction in the refrigeration system. Is there a way to tell if the control valve is bad by the readings on the refrigeration gauges, or is there another test they can do to see if that's the problem?

mk378 on Tue December 14, 2010 8:07 PM

Put the interior fan on low and rev up the engine to typical driving rpm. If low side goes down below 20 psi, control valve is bad. If it doesn't but still freezes, the refrigerant would be contaminated by air from improper charging (at the factory?), and it needs to be removed down to a full vacuum then recharged with new refrigerant. As GM Tech said, those are the two reasons for freeze up of a variable compressor system.

Freezing of the evaporator is not normal. This should all be covered by your warranty as it's a new car.

Edited: Tue December 14, 2010 at 8:11 PM by mk378

jyesluga on Fri December 17, 2010 6:36 PM

Just wanted to update the status on this issue...
Just got my car back from the dealer, and they reported that the pressures on the a/c system were 116 high side, 16 low side. The tech was advised to replace the TXV valve, which he did. The pressures went up to 184 high side, 18 low side. The tech was then advised to replace the compressor, now the pressures are 174 high side, 26 low side. No more evaporator freeze up!!

NickD on Sat December 18, 2010 9:06 AM

Good idea not to fool with any item under warranty, can void the warranty. But do tend to check the workmanship of the repair to make sure everything was put back where it came from and all the bolts are tight.

jyesluga on Sat December 18, 2010 7:42 PM

I checked under the hood when I got the car home, as I always do after a vehicle repair, and everything seems to be working correctly. The only thing is, the compressor is so far out of reach from the top that I couldn't check any fasteners for tightness, but it does seem to be working as it should. Thanks for the help on this one!!