I want to isolate my AC issue before I have a repair made.

I measured the pressure reading in 81 degree weather:
Engine Off: Low is 95 psi and High is 98
Engine On and AC On: Low is 98 and High is 99.5

For compresser clutch test, many non-s2000 cars are tested as follows:Looking over the S2000 service manual, it is not clear to me whether this test applies for the s2000.
On mine, when the belt is removed, the front turns freely with the pulley as if a single unit. When the belt is installed, neither the front nor the pulley can be turned by hand.
It is as if the pulley and front of the compressor are a single part.
Do these results suggest the clutch is locked?

I have confirmed that my compressor relay is not defective. My engine rpm kicks down when I turn on the AC in the car. This suggests to me that the clutch engages correctly.

Suggestions on isolating the defect?!

Thanks.

 

How are you measuring pressure?

when AC is off car off high side and low side pressure should be equal. When you turn the car on and run the compressor for ~10 minutes you should have between 40-60 psi low side and 150-170 psi high side. If you run the compressor and you don't get a pressure differential then your compressor ain't compressin'.

If your compressor ain't compressin' then you need a replacement. I HIGHLY recommend the OEM Kehin compressor brand new. You do not have to buy it from Honda.

When checking readings on your manifold gauge, assuming you have one, use the green numbers as that is the reading for R134, do not go by the atmospheric pressure reading.

As for your other concern, you will find it difficult to turn the AC clutch by hand because the pressure in the system acts as internal resistance. The AC pulley freewheels with the rest of the engine pulleys, once the AC clutch is engaged the compressor pulley becomes locked to the compressor shaft and drives the compressor(hence the rpm bog).

 

All I will add at this point (it IS Friday night) is you can see if the compressor is activated by popping the hood with the ac running. It will cycle on and off as the magnetic clutch engages. That is normal. If it engages you will see it rotate. You still could be low on R134 but you know there is enough in there to troubleshoot the compressor operation.

 

Have you ever heard of the clutch falling off (photos below)? That explains why the front of the pulley appeared to be spinning when the AC was off.

So how do I proceed on this:

a) Get a new clutch and just attach clutch while keeping the same electro magnet and pulley? This assumes that the bolt didn't break off. What do you think - is the whole bolt there? It also assumes that the compressor is still good.

a') replace the entire clutch mechanism (magnet, plate and all).

b) Replace the compressor with clutch and assume there was no internal compressor failure with shards of metal blasted into the system.

c) Assume catastrophic failure and replace the compressor, condensor, and possibly the dryer.

(To answer the question, I used Yellow Jacket 42006 with Yellow Jacket Low/High Connectors. I did not allow the system to run for long but it wouldn't have mattered).

 

Never seen that happen before. You're probably fine replacing the magnetic clutch.

 

That's....strange.

 

I'm the only owner of this car, bought in 2006. It has never had AC service.

it is strange.

here is a theory: the compressor failed and locked while the engine was running. the stress caused the clutch to break loose.

It looks serviceable without removing the compresser, perhaps a wasted effort if the unit locked.

 

surprisingly broken off compressor clutch is reported many times in this and other groups for s2000. It is also mentioned more generally against honda and accura.
People assume that the compressor locked and end up paying a lot of $$$ for a new compressor.

Here is an 2013 recall of acura addressing the failure to apply anti-corosion conditioning on the shaft or nut resulting in the clutch falling off:

https://honda.oemdtc.com/437/jq7-saf...2015-acura-mdx

My photo above shows rust on the threads.

My compressor turns ok - definitely not seized. So I will try replacing the clutch and report back!

 

Odd. Never heard of a recall on any of the Honda/Acura cars which I've owned.

 

It worked. The clutch kit costs about $90. The honda oem nut cost a couple of dollars and so did the tube of nut lock.

I took the air filter housing off for easier access. All I did was put on the plate (and a couple of shims). The bearing and coil remain original. I was able to use a screw driver to counter against a torque wrench. (the proper tool (ac clutch holder) is available on amazon for $10 but I didn't want to wait.

well i wasted a couple hundred getting a manifold set with connectors. but increased my knowledge.

I bet person after person has been ripped off having been told their compressor was shot, new evaporator, etc.

Hah!