AC stopped working after tire change

[TheBirdie72]

Have you tried putting the old tires back on to see if it resolves the AC problem? I mean…logically…

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[AlgUSF]

Interesting, that's news to me and my store doesn't appear to be doing them. I suppose I understand it being so related to tire wear, but hate for it to potentially take away from focusing on one thing and doing it really well. But I stand corrected...

Either way, still doesn't support them intentionally draining his A/C in hopes of getting additional work to perform.

I agree, there would be no profit motive for DT to touch the OP's A/C.

I was hoping Discount Tire would start doing alignments, but I wouldn't want them to venture too far down the road. Doing tires well is what sets them apart from the competition.

 

[Eyeball]

Correlation does not imply causation

 

[roaniecowpony]

Hopefully, it's something simple like a pressure transducer or connector.

 

[alphawolff]

I have some automotive background and am confounded as to what could have possibly happened. Yet no prior AC issues. Blew cold air on the way to the shop. Just outside air when I left.

AC clutch is not engaging. I did finally find some adaptors for r1234 and I hooked it all up and my hoses leaked like a sieve. I haven't used them in a while so maybe seals have dry rotted or perhaps just not made for r1234. Needless to say, I didn't get to do any testing...however, the high side did shoot up to at least 125 psi (not running) before I clamped it all back down again. I would imagine that would be enough refrigerant for the system to work.

I'm fairly certain it's electrical in nature now, but still, what could have possibly happened? I know the JLs have electrical gremlins and any sort of odd thing can affect other systems. So who knows?

I feel like the odds of a perfectly working AC failing at the exact moment it is in the shop and the odds of changing tires could have done something to the AC are equally low. But here I am. One of the two happened.

Most likely a completely random failure and unrelated to the tire change. That being said, diagnostic for a non-functional A/C is *very* straight forward on our vehicles. You should gain access to a scan tool that can parse PCM & hvac module data.


1. Turn the A/C on
2. Using the scan tool, verify the A/C on command is being read AND the A/C clutch is being commanded on. Depending on the values it leads you down completely different diagnostic paths.

A/C command not being read? Bad HVAC module or button perhaps (it probably wouldn't light up)

Clutch being commanded on but compressor isn't engaging? Disconnect clutch connector and verify it's getting power and ground. Go from there, if it is, replace it. If it isn't, you're now doing command circuit diagnostic.

Clutch not being commanded on? Most likely low on freon. Verify leak and re-charge.

Clutch being commanded on AND clutch is spinning? Perform A/C actuator test to confirm it isn't a blend door issue. You can also verify evaporator temperature and evaporator temperature target as an alternative using the scan tool. (evaporator at 40f but not cold at the vents? blend door issue) If not a blend door issue, evacuate the system to verify it is charged. If it is, replace the compressor. If it isn't, find the leak.


I see too many techs going down a rabbit hole of checking power (fuses) before even verifying the PCM is commanding the damned thing to turn on. Drives me bonkers seeing time wasted like that. You can see the hi-side pressure with a scan tool, but it isn't the most reliable. I've seen systems read 80 psi and be empty. The hi-side scan tool pressure should be about equivalent to the ambient temperature (80psi = 80f ambient). This figure is assuming the system hasn't been running recently. I would frankly ignore this readout other than verifying compressor cycling, but I brought it up because it's useful information. Sometimes it'll read 80 psi, engage the clutch, and it spins, but nothing gets cold. It's because it's just compressing air, not Freon. Again, don't trust that readout for more than general information.

 

[Rogue321]

Most likely a completely random failure and unrelated to the tire change. That being said, diagnostic for a non-functional A/C is *very* straight forward on our vehicles. You should gain access to a scan tool that can parse PCM & hvac module data.


1. Turn the A/C on
2. Using the scan tool, verify the A/C on command is being read AND the A/C clutch is being commanded on. Depending on the values it leads you down completely different diagnostic paths.

A/C command not being read? Bad HVAC module or button perhaps (it probably wouldn't light up)

Clutch being commanded on but compressor isn't engaging? Disconnect clutch connector and verify it's getting power and ground. Go from there, if it is, replace it. If it isn't, you're now doing command circuit diagnostic.

Clutch not being commanded on? Most likely low on freon. Verify leak and re-charge.

Clutch being commanded on AND clutch is spinning? Perform A/C actuator test to confirm it isn't a blend door issue. You can also verify evaporator temperature and evaporator temperature target as an alternative using the scan tool. (evaporator at 40f but not cold at the vents? blend door issue) If not a blend door issue, evacuate the system to verify it is charged. If it is, replace the compressor. If it isn't, find the leak.


I see too many techs going down a rabbit hole of checking power (fuses) before even verifying the PCM is commanding the damned thing to turn on. Drives me bonkers seeing time wasted like that. You can see the hi-side pressure with a scan tool, but it isn't the most reliable. I've seen systems read 80 psi and be empty. The hi-side scan tool pressure should be about equivalent to the ambient temperature (80psi = 80f ambient). This figure is assuming the system hasn't been running recently. I would frankly ignore this readout other than verifying compressor cycling, but I brought it up because it's useful information. Sometimes it'll read 80 psi, engage the clutch, and it spins, but nothing gets cold. It's because it's just compressing air, not Freon. Again, don't trust that readout for more than general information.

I brought it to the dealer and went on vacation. They replaced the compressor. Not cheap.

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