AC Gone again- help?

[RandyH2]

The air conditioning went out about 4 years ago (to the month) on one of the hottest days of the year. Now it has done it again just as a heat wave hits Michigan. The dealer can't get me in until August 8th so I would appreciate any troubleshooting tips from folks who know.
I've visually checked two 10A fuses under the hood and could not get the square relay/fuse (#98?) out to check it.
I can hear a click sound when I turn the AC on.
I may have heard a click/clank/thunk sort of noise, not all three just a single noise, immediately before losing the cooling. Sound may have come from drivers side front?
The fan blows fine. I let it sit overnight, etc. without any change.

Thanks,
Randy

 

[RandyH2]

A bit more info:
When the AC is turned on the engine sounds normal.
When the AC is turned off the compressor makes a dry bearing, metal-on-metal sound that continues as long as the compressor is turned off but goes away immediately after the click when the AC is turned back on.

 

[Harpua216]

sometimes that sound is one of two things. a bad clutch bearing or lack of lubricant (or freon) in your system.

I also happen to think you may have the recirc door falling on your blower fan. this will push hot air from the outside and mix cold air with hot and making you think your AC isnt working. if you lower the glovebox down and put your fingers in the vents and feel downwards, see if you can feel the door on the bottom above the blower motor.

I am also wondering if the pop you are hearing is the blend door actuator starting to fail or failing in your case.

 

[RandyH2]

Thanks for the suggestions. I'll bring a manifold gauge home and check the freon and check the door. I only heard the "pop" noise the one time. Hopefully (!!!) it was freon going all at once from some obvious place and not something mechanical.

 

[peterk9]

Thanks for the suggestions. I'll bring a manifold gauge home and check the freon and check the door. I only heard the "pop" noise the one time. Hopefully (!!!) it was freon going all at once from some obvious place and not something mechanical.

Not sure that they are still using "Freon" any longer. The door behind the glovebox is the 'Blend Door'. There are a couple of threads on that where the door was stuck in one position or the other resulting in either hot or cold air being blown. The fix was usually replacing the blend door actuator.

Peter

 

[RandyH2]

"Freon" is a bit like "Kleenex", now I know. Still, we know what is meant and it rolls of tongue better than R-410a/R-134a or whatever.

Diagnostic question:
It cooled off after a rain today. Outside temp is indicated at 71 degrees F. Max A/C setting, which forces recirc mode, still only blows ambient temp air. If it were the blower door, wouldn't the cooler ambient air mixed with cold conditioned air give a noticeable temperature change?
Neither of the A/C lines under the hood has a distinct temperature change either, both feel ambient or slightly warmer, no matter where I touch them within easy reach.
.

 

[RandyH2]

More diagnostic:
Rear climate controls do not impact cooling: fan hi/low/off, rear control on/off.
Heat works, dual zone control works with heat on one side, "cooling" on the other. "Again, cool is only ambient.
Recirc seems to work, I can definitely hear the gate motor running and a change in fan/air flow sound.
Not knowing exactly how the system works, I am assuming the "door" controls fresh air flow and my tests seem to indicate that it is functioning normally, correct? Are there separate doors for blend and recirc?

At this point the lack of temperature differential in the lines seems to indicate either loss of refrigerant or clutch/compressor problem?


Thanks,
Randy

 

[RandyH2]

And a word of warning for the next guy: DON'T check the refrigerant pressure at the valve closest to the windshield washer reservoir. If it is under pressure and you simply poke it with a screwdriver you'll have fluorescent yellow stuff all over your hood, etc. Yep, learned that one the hard way.
The other valve, closer in size to a tire valve and closer in location to the firewall, gave an air hiss like venting an air compressor, no nasty yellow stuff. The big one was an almost explosive release of pressure.

So, it seems I have good refrigerant pressure ....

 

[RandyH2]

One other possibility I suppose- the APIM going bad (again). SYNC has been acting a bit weird lately, black screen, sluggish, etc....

 

[RandyH2]

The blower door behind the glove box appears to be operating- it definitely goes through the motions of opening and closing with changes in HVAC settings. As an aside, the interior/cabin air filter was nasty. Gave it a good cleaning while I had everything apart.

I also disconnected the power/system cable from the blower assembly, no better.

I did a SYNC Master Reset too. No change.

 

[reserved50]

is the front part of the a/c compressor (a/c clutch) engaging(spinning with the pulley) when the a/c is on?

 

[RandyH2]

Yes, sorry I forgot to mention that. It goes from idle to rotating just fine, seems to rotate at the "right" speed relative to the belt bu that is just casual observation, no scope on it or anything.

 

[reserved50]

then it should be blowing cold air , did it stop all of a sudden? Touch the lines that enter into the passenger compartment from the engine side, one line should feel ice cold if the a/c clutch is spinning like you said. If not maybe the system has a leak is full of air or moisture.

 

[RandyH2]

then it should be blowing cold air , did it stop all of a sudden? Touch the lines that enter into the passenger compartment from the engine side, one line should feel ice cold if the a/c clutch is spinning like you said. If not maybe the system has a leak is full of air or moisture.

None of the lines feels cool. The larger line (gas line?) feels warmer than the other but neither is even close to being cool or cold, certainly not 30-50 degrees from ambient. The small line coming off the compressor going to the condenser is not cold.

The low side pressure, at 90 degrees ambient and a hot engine, is about 140 psi with AC set to Max AC. I don't have access to a high side gauge yet.
Note that the pressure was about the same after the engine had been off for a few minutes.

 

[reserved50]

if the clutch is engaging and internally the compressor is ok and none of the lines are cold you may have a leak, your system may be full of air/moisture is my guess. If any of the lines were cold you would have a problem with the mix motor area that changes from hot to cold. If the lines feel about the same temperature with a/c clutch working I'm out of ideas.

What did they replace last time? You shouldnt hear the a/c compressor making an obvious sound when its on, maybe it failed?

 

[peterk9]

if the clutch is engaging and internally the compressor is ok and none of the lines are cold you may have a leak, your system may be full of air/moisture is my guess. If any of the lines were cold you would have a problem with the mix motor area that changes from hot to cold. If the lines feel about the same temperature with a/c clutch working I'm out of ideas.

What did they replace last time? You shouldnt hear the a/c compressor making an obvious sound when its on, maybe it failed?

The odd thing is that the noise is only present when the compressor is OFF. Post 2.

Peter

 

[reserved50]

The odd thing is that the noise is only present when the compressor is OFF. Post 2.

Peter

that would mean the pulley bearing is going bad, either way it does sound like the compressor is on its way out if its making a noise

 

[RandyH2]

The odd thing is that the noise is only present when the compressor is OFF. Post 2.

Peter

Yep, and intermittently at that. Since the clutch is stationary when disengaged I am guessing something in their is rubbing/dry. So far none of the easy/obvious fixes have worked and I am disappointed- and sweaty.
Several of the videos/posts I have seen strongly advise not pumping random amounts of refrigerant into the system yet many people report success fixing their problem that way. Mine seems to have an overpressure situation but that can't be trusted off of the cheapo gauge I only had on the low pressure side. Hopefully get it in to the local mechanic tomorrow for a quick assessment.

 

[reserved50]

Adding random quick fix refridgerants like some do on the internet to the a/c system will help it not last very long. Kind of like filling your engine with cooking oil. Either way it sounds like its going to cost a few hundred to have a it properly repaired.

 

[derby4u99]

If your low side pressure is 140 psi either the compressor is not running or it has a mechanical failure internal to the compressor. Or you were connected to the high side. You should see 35-50 psi running on the suction side and 140-200 on the liquid line.
An under hood temp of 107 deg. would give you 140 psi on a dead system