Hi,
I own an auto workshop in UAE and do alot of AC repair on many cars. One of the problem I can't really find its source is the newer altima ac system. Many customers complain of hot air from ac vent to find that the compressor is jammed or got no pressure at all. Ac line full of black burnt oil and complete system need cleaning. We replace compressor, condenser and expansion valve and then everything seems fine until fee months compressor gets damaged again. I found later that there is a problem with ac thermostat that just let the compressor run even if it is cold and when driving on highway the ac line freezes and that what causes compressor failure.
The problem is that i couldn't find a thermostat near evaporator or inside glove box like the rest of other cars so how can I fix this issue? Once solution is to install a manual thermostat and attach it to ac suction line but I want to know if the issue is from AC ecu or there is cabin air thermostat somewhere I'm missing.
Couldn't make them customers wait till I find an answer online so had to install manual thermostat inside evaporator to cycle them compressor. Anyone got an idea how to solve the issue of freezing ac line on altima because I couldn't find the factory thermostat anywhere.
Tim wrote:American Market versions of this vehicle use a variable displacement compressor. So no thermostat is needed.
Hi Tim,
Thank you for sharing this info. Regarding the US altima it does have a mechanical control valve
I did replace the compressor and even the sensor new but the AC would still keep working and ac line and evaporator would freeze up. I worked on many cars with mechanical and electrical control valve and I found they had thermostat in the evaporator.
1) The manual control valve bleeds gas to control the crankcase pressure to change the differential pressure across the underside of the piston verses the piston top which in turn changes the swashplate cam angle or stroke and refrigerant mass flow. Early versions had internal filters which would stop up with trash and fail therefore filters were usually eliminated.
2) Border line system capacity designs (some VWs) took the factor of safety out of the control valve calibration. Freeze up protection could fail so a freeze protection thermal switch was added.
3) Maybe higher ambient (UAE) reduce the factor of safety because of a suction pressure over ride internal to some valves overcomes the primary control gas bypass flow rate. In other words, the suction pressure says "my passengers are not cold enough therefore I'm keeping the cam at a large angle" and operating closer to evaporator icing.
hotrodac
ice-n-tropics wrote:1) The manual control valve bleeds gas to control the crankcase pressure to change the differential pressure across the underside of the piston verses the piston top which in turn changes the swashplate cam angle or stroke and refrigerant mass flow. Early versions had internal filters which would stop up with trash and fail therefore filters were usually eliminated.
2) Border line system capacity designs (some VWs) took the factor of safety out of the control valve calibration. Freeze up protection could fail so a freeze protection thermal switch was added.
3) Maybe higher ambient (UAE) reduce the factor of safety because of a suction pressure over ride internal to some valves overcomes the primary control gas bypass flow rate. In other words, the suction pressure says "my passengers are not cold enough therefore I'm keeping the cam at a large angle" and operating closer to evaporator icing.
hotrodac
This makes alot of sense
It is true that these US import altima don't have these problems until they arrive here in UAE. I have to check for a Gulf spec altima and see what was changed to solve this. Only US import have these issues here.
Thank you very much for your help.
