AC Diagnosis?

[EddieC]

2008 Tahoe;
Today our air conditioner blew nothing but hot air even though the hvac display light was on.
We've never had an issue with it before and it generally blows icy cold, at least in the last memory of serious,y using it. I say seriously because we are just coming into the season but the auto settings turn the ac on frequently. It has never needed attention in the past.

I checked three fuses and swapped out one relay, all which appeared ok, then upon closer inspection I found the compressor clutch engaging for only 3 seconds and then running 12 seconds disengaged, then repeat and repeat when the ac was turned on.

I ran out for a recharge kit and on the initial test the gage showed needing a charge. Using a 20 oz can it took most of the refrigerant but did get in the green zone on the gage near the minimum acceptable pressure of 30 psi.

Once the charge was started to be applied the compressor clutch would stay engaged as it should.

Now the air from the ac vents is cool, not cold. Took it out for a ride and it seemed a bit cooler, but again not cold as I remember. There was a definite difference between ac off and ac on though.

Fingers crossed that it holds the charge in the coming days. I am not understanding why it doesn't seem as cold as it seems to have been all (?) of it's previous long life.

Any input would be appreciated from those who have been through it or are familiar with the system.

 

[LordWayback]

short of running some dye in there you could change out the valve cores next time it gets refrigerant

 

[LordWayback]

It sounds like a slow leak getting faster over time you should get a dye kit with a uv light and add dye with the next r134a fill up and check all the common places, pulley shaft seal, compressor body seal, condenser, where the fittings meet and if you have rear AC check in the inside of the passenger rear fender liner with the uv light sometimes the rear ac lines like to catch road salt and corrode there or the hangers wear them out otherwise check the evap drains if either Evap drain has dye (with rear ac) then you have a expensive repair job to make as it indicates the evaporator cores being bad

 

[EddieC]

It sounds like a slow leak getting faster over time you should get a dye kit with a uv light and add dye with the next r134a fill up and check all the common places, pulley shaft seal, compressor body seal, condenser, where the fittings meet and if you have rear AC check in the inside of the passenger rear fender liner with the uv light sometimes the rear ac lines like to catch road salt and corrode there or the hangers wear them out otherwise check the evap drains if either Evap drain has dye (with rear ac) then you have a expensive repair job to make as it indicates the evaporator cores being bad

Thanks for that.
I never knew that the rear ac was more than just ducting.
This is going to need a video search.

 

[LordWayback]

Thanks for that.
I never knew that the rear ac was more than just ducting.
This is going to need a video search.

If you look under the vehicle by the passenger rear wheel well you can see where the coolant hoses and refrigerant hoses go into the rear evaporator box

 

[opfor2]

If you look under the vehicle by the passenger rear wheel well you can see where the coolant hoses and refrigerant hoses go into the rear evaporator box

Rear AC connector

 

[LordWayback]

Rear AC connector

Correct, also in the wheel well there are plastic clips on the frame which is where the rear lines typically leak

 

[LordWayback]

Thanks for that.
I never knew that the rear ac was more than just ducting.
This is going to need a video search.

This is the specific clip where the lines like to fail inside the wheel well 99-modern rear ac i believe all run a similar clip design

 

[EddieC]

I haven't been able to get back to mine but hopefully soon.