Open the hood, find the AC compressor, have someone turn the AC compressor on and off. Watch the AC pulley, and you'll know when the compressor is engaged.

Are you getting cold air?

 

Sorry, I should have explained at the beginning that our AC is not putting out any cold air. I believe it is fully charged. The AC compressor pulley turns when the engine is on, but the compressor clutch does not engage at all when AC is turned on.

 

Did you try swapping the AC relay? I believe there are 3 identical relays there in the fusebox.

 

Yes, I tried swapping the relays. Nothing made the AC clutch engage.

 

@sherjo, have you ever had your A/C system serviced?

I'm asking about where the automotive HVAC tech evacuates all of the refrigerant, pulls vacuum, and then recharges with the proper mass.

OF

 

We've never had the AC system serviced.

 

You probably need to have your AC system professionally evacuated and recharged as stated in #6 above. This needs to be done about every 8 years or so. A low charge in the system will prevent the compressor from engaging. Also, even if your AC clutch relay is good, you should upgrade to the new and improved Mitsuba relay.

 

Believe =/= know

 

Attached a gauge, it read slightly low.
Added small amount to spec. Avoided over filling as that can cause the system to not work. The previous/original owners had all service done at Honda dealerships and kept all records. We are out of state so cannot access that information. However, the air conditioner previously would freeze us out. Very cold.

I want to point out that the electrical test of the empty compressor relay socket (see my description of test in my first entry, above) appears to point to an open in the clutch coil.

My original question:
". . . how can I be sure the problem is confined to the clutch coil and not the compressor?

"When I turn on the air conditioner, I see the rpms dip slightly (and radiator fans come on). Is this all I need to verify that the compressor is working?"

 

Attached a gauge, it read slightly low.
Added small amount to spec. Avoided over filling as that can cause the system to not work. The previous/original owners had all service done at Honda dealerships and kept all records. We are out of state so cannot access that information. However, the air conditioner previously would freeze us out. Very cold.

I want to point out that the electrical test of the empty compressor relay socket (see my description of test in my first entry, above) appears to point to an open in the clutch coil.

My original question:
". . . how can I be sure the problem is confined to the clutch coil and not the compressor?

"When I turn on the air conditioner, I see the rpms dip slightly (and radiator fans come on). Is this all I need to verify that the compressor is working?"

Swap out the coil and see if it resolves your issue. It isn't expensive nor it needs system to be emptied and refilled.

 

You added refrigerant yourself, from a canned kit I'm assuming. Those gauges will not tell you the volume of refrigerator in the system, only the pressure. This may be okay on a fully evacuated system, but definitely not without knowing what's in there. Those cans are also capable of blowing seals.

 

Thanks for all the helpful responses. Turned out the compressor had seized so had a mechanic replace it, recharge etc.

 

Yikes! You may have damaged your compressor when you added refrigerant yourself.

 

I'm just about convinced that this godd@mned company is responsible for more ruined HVAC systems than all other snake oil A/C "repair" companies combined.

OF