I recently had my AC charged. I talked extensively with the tech about the specific hybrid epag oil and needs. They seemed competent. I trusted them. Two days after charging up my car started throwing a check engine and 12v battery light if I turn the AC on. Turn it off and restart the car and everything works as normal. The shop couldn’t troubleshoot it and even Honda could not readily identify it.

Anyone ever experience this before? I hate to just throw money at parts like a new compressor if it isn’t going to fix the problem. There are no apparent problems with DC-DC converter although maybe it is failing under load.

IMA light is on and has been. My attempts to deep discharge and grid charge have brought back a lot of life and raised gas mileage but have not gotten rid of the light. No other issues.

 

Having purchased 50mL of the precious fluid myself for $64 when I replaced my compressor, I'm pretty sure the oil is ester based, not PAG. If you were just refilling because it was low, pure R-134a would have been fine, and you could have done it yourself for $23.

You have indicated you have CEL and IMA lights on, but you have reported no codes. That's like going to the doctor for your sore foot but refusing to remove your shoe. Doc's going to tell you he can't help you if you won't let him see your foot.

Car is trying to tell you what's wrong. Listen. IF you don't have a code reader, turn car off, short pins 4 and 9 on the OBDII connector , turn ignition on (no start), count out slow fast blinks of CEL and IMA light. Video it to capture it and don't stop until you see both patterns repeat.

 

I apologize! Didn’t mean to withhold. My scanner is a cheap one that doesn’t seem to be able to read these codes. Need to invest in a real one. I should have grabbed The paperwork from Honda though. Honda pulled a P0AA6 code.

i agree I could have done myself and now wish I had. I usually do but I wanted for once to have a competent specialist make sure there wasn’t something going on in the system that was more than charge-related. Feeling like that was a mistake though as all it was doing before was blowing warm when at stop lights...

 

Apologies. My code scanner doesn’t seem to properly read the codes but I was able to grab what Honda scanned. It is pulling a P0AA6 only when the AC is turned on.

Below are the notes from the tech.

 

The picture you posted is infinitely more valuable than the vague ramblings of your initial post. Given the previous example, not only do you refuse to take off your shoe for the doc, but you also neglect to tell them you've severed your big toe. And not only are you not telling them you severed your big toe, you tell them you haven't. The dealer DID figure it out, yet you said they didn't.

P0AA6 is an HV isolation fault indicating HV path to chassis ground when they are normally isolated.

The A/C compressor is likely internally shorted due to improper oil, or it was always bad, and now you're having problems because you attempted to restore it to function. However, the short can occur in the IMA motor, inverter, etc. Given the behavior occurs when you turn on the A/C, I would expect it to be the A/C.

Turn off battery master switch. Disconnect A/C power cable in engine compartment and use Megohm tester set to 250V to measure resistance between each of the 3 terminals on the cable to the compressor to body ground. Any resistance less than 350kΩ is a fail. If you don't have a megohm tester, you can try a regular multimeter ohmmeter, but you can't trust the number as an absolute.

 

You’ve got me dying man. I appreciate both the commentary and the tips for how to test. I honestly thought I’d get crickets. Talking with them, they were not so definitive in the diagnosis. Perhaps that was because he wasn’t the tech but the “customer service” guy. They said, well, since it’s an old car you don’t want to pour endless money into, we skipped these 53 steps and are pretty sure it’s bad compressor oil.

Call the AC shop and they swear it isn’t them.

i was just worried about throwing parts at it guessing.

I appreciate the testing tip and the time you took to respond. I see you all over these boards and your input is awesome. Thanks for taking the time to give it.

 

Unfortunately, the dealership service folks one deals with know so little, and they rarely bother to read everything on the output from the tech. They're just trying to get your money and get you gone, so they can move onto the next commission.

When my compressor went bad, I picked up a lower mileage compressor from a salvage yard for $130. A vacuum pump from Harbor Freight or Amazon for $100, 50mL honda hybrid compressor oil for $64, Manifold gauges for about $40 and 3 cans of Walmart supertech R-134a for $4.88 each. I also replaced the expansion valve under the dash on the firewall for about $40. I didn't need one, but I did that first hoping it would fix everything.

I did have to shim the new compressor clutch. I just used the shims from both to get the gap right (needed more shims on the replacement).

I really didn't need the compressor oil The one I got already had a good amount in it. No, I didn't precisely get the right amount of oil in the system, but it worked out nicely.

About $400 total and a day to get it replaced vs. the dealership $2200.

If the A/C was working, but was weak before you had it filled, the shop screwed up. If the function of the compressor was uncertain when you took it in, the failure could have been already present, but never threw a code because the compressor never engaged.

Something that might be worth trying is to disconnect the electrical connector making sure you protect both ends from contamination during operation, and see if the A/C will work on the mechanical compressor alone. I doubt it will, but it's an easy check.