Automotive Air Conditioning Information Forum

2012 Honda Odyssey:


Brand new Denso Compressor, when charging the system, the pressure relief valve on the bottom of the compressor will begin to purge refrigerant @ Low: 35psi High: 110psi. Ambient temp about 71F.

Observation: The clutch seems to always be engaged and will not cycle on/off.

I checked and replaced the Clutch relay just to rule that out.


I’ve done a lot of A/c work but this one is giving me a headache…

It would seem the valve is bad. New no longer means what it did years ago. It won't cycle because it is low on charge. Hi of 110 isn't much. Are you weighing in the charge or winging it?. If weighing, how much is in there now, and what is the capacity. What other work was done?

tbirdtbird wrote: ↑Tue Apr 19, 2022 9:05 pm It would seem the valve is bad. New no longer means what it did years ago. It won't cycle because it is low on charge. Hi of 110 isn't much. Are you weighing in the charge or winging it?. If weighing, how much is in there now, and what is the capacity. What other work was done?

The reason we decided to replace the compressor was because it was doing exactly that (purging before hitting target pressures.
I’m not weighing the refrigerant but it won’t even take two 12oz cans before it begins to purge out.

OK. What is the system capacity?

Let's wait for another regular consultant to weigh in on this

tbirdtbird wrote: ↑Wed Apr 20, 2022 7:35 am OK. What is the system capacity?

Let's wait for another regular consultant to weigh in on this

About 25 oz

For a 2012 Odyssey with a 3.5L 6-cylinder engine, my sources specify 27.0 ounces net weight of R-134a and 4.2-4.6 fluid ounces of PAG-46. If the vehicle has an under-hood decal with the A/C specs imprinted on it, the decal would take precedence if the specs differ from the former.

I agree with a foregoing comment. The reason the HPRV would release at only 110 PSI is if the valve itself is defective--that is, not seating properly. Remember, "NEW" means "Never Ever Worked." I'd try replacing the HPRV valve on the new compressor with another new valve.

JohnHere wrote: ↑Wed Apr 20, 2022 2:50 pm I agree with a foregoing comment. The reason the HPRV would release at only 110 PSI is if the valve itself is defective--that is, not seating properly. Remember, "NEW" means "Never Ever Worked." I'd try replacing the HPRV valve on the new compressor with another new valve.

What are the odds that the new compressor failed in the exact same way as the old one? Slim to none.

The new compressor is not cycling, it’s staying on… Could the climate control unit be bad, forcing the clutch to remain engaged?

I'd like to see what John would say.
But we have all seen bad runs of certain parts.
We saw a bad run of TXVs here a few years ago (nothing whatever to do with Tim's parts) (the site owner)

I can relate. I think most of us on here have gotten headaches with problems like this. I'd still start with replacing the HPRV. They're cheap, and at least then we could rule it out.

Do I understand correctly that you can charge the system only to a reading of 110 PSI on the high side (when it should be about 160 PSI at full charge and at 71 degrees ambient) before the HPRV starts to release? If so, the reduced high-side pressure could be the reason why the compressor isn't cycling yet. How much refrigerant does it take before the HPRV starts to release?