33 GTR aircon air flow slows after running for an hour

[believer]

Hi Guys

Has anyone come across this problem with the aircon air flow slowing down to almost no air coming out of the vents after the aircon has been running for about an hour? The air flow will return if you turn off the AC for maybe 15-20 minutes If you run the AC again, the air flow will slow down again after a few minutes.

Cheers.

[GTSBoy]

Is it on auto?

[joshuaho96]

8 hours ago, believer said:

Hi Guys

Has anyone come across this problem with the aircon air flow slowing down to almost no air coming out of the vents after the aircon has been running for about an hour? The air flow will return if you turn off the AC for maybe 15-20 minutes If you run the AC again, the air flow will slow down again after a few minutes.

Cheers.

If it isn't the fan speed going down your evaporator core is almost certainly freezing over. Get the system evacuated and checked for leaks, then verify the compressor is working correctly.

[GTSBoy]

14 minutes ago, joshuaho96 said:

If it isn't the fan speed going down your evaporator core is almost certainly freezing over. Get the system evacuated and checked for leaks, then verify the compressor is working correctly.

If it's freezing the evap core over, then it's not a leak/gassing problem, or a compressor problem. It would be a TX valve problem, not cycling the compressor off when the core gets cold enough. So either the TX valve stuck or the temp sensor come off the core.

[joshuaho96]

14 minutes ago, GTSBoy said:

If it's freezing the evap core over, then it's not a leak/gassing problem, or a compressor problem. It would be a TX valve problem, not cycling the compressor off when the core gets cold enough. So either the TX valve stuck or the temp sensor come off the core.

I've had a new car with evap core freezing issues, seemingly related to low refrigerant charge. So not impossible but worth checking.

[GTSBoy]

Ignore. Typed a fluffy answer.

Edited February 7, 2023 by GTSBoy

[believer]

Thanks for all the replies.  

How hard is it to get to the TX valve and the temperature sensor on the core?

 

[GTSBoy]

4 hours ago, believer said:

How hard is it to get to the TX valve and the temperature sensor on the core?

Dunno on a 33. The core is buried under the dash on any car and is no fun to get to. The TX valve could be also, or could be on/near the firewall behind the turbos.

It's a job for a fridgy anyway.

Edited February 8, 2023 by GTSBoy

[Ty1]

On 08/02/2023 at 1:40 PM, believer said:

Thanks for all the replies.  

How hard is it to get to the TX valve and the temperature sensor on the core?

 

Super easy! You will need to get the ac degassed before you attempt to remove it. Remove the glovebox, then you can get access to the heater box and undo the 2 ac lines that poke out from the firewall near the turbo. I'm sure there are many detailed threads on this already.