This is on an 06 SLK280. Obviously blowing hot air. Compressor doesn't disengage, and the high and low side pressures are both at 140psi. All tubing is the same temp. It was last evacuated/vacuum tested/filled up by machine.

How would it just stick at 140psi on both sides? If the compressor is bad, shouldn't it be at the 55-ish that the low side was filled to? Obviously the high side is low, but the whole system is now equalized. I haven't ever seen that.

What gives?

This post was edited on 7/10/18 at 10:04 am

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Posted by bbvdd

Memphis, TN

Member since Jun 2009

25088 posts

Posted on 7/7/18 at 10:39 am to Hammertime

Do you hear the clutch kick in at all?

ETA: I really don’t know anything about the pressure of it.

My wife’s MDX was blowing hot air and it was the clutch relay went out.

This post was edited on 7/7/18 at 10:40 am

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Posted by Redlos

Baton Rouge

Member since Jul 2005

1051 posts

Posted on 7/7/18 at 11:22 am to Hammertime

Prob a bad compressor, gauges are “closed” and reading same pressures?

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Posted by ScottyB

Member since Apr 2016

39 posts

Posted on 7/7/18 at 12:05 pm to Hammertime

It's probably the front sam (fuse box under the hood by the booster). It's what powers the compressor on that vehicle. Check and see if you have power at the compressor. If not, that's most likely the culprit

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Posted by windmill

Prairieville, La

Member since Dec 2005

7024 posts

Posted on 7/7/18 at 12:13 pm to Hammertime

Make 100% certain the clutch is indeed engaged. Gauge dials closed . Equalized pressures of 140 under these conditions would indicate a bad compressor. The shaft of the compressor is broken or it's completely worn out. I want to know what the static pressure of the system is.?

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Posted by kew48

Covington Louisiana

Member since Sep 2006

1116 posts

Posted on 7/7/18 at 5:02 pm to Hammertime

If the compressor is engaged and pumping then you have a bad compressor. That 140 sound like the saturated pressure at 90-95 degrees for 134A.

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Posted by Spankum

Miss-sippi

Member since Jan 2007

56126 posts

Posted on 7/7/18 at 7:12 pm to Hammertime

Check to see if the compressor clutch is really not disengaging by unplugging the wires that lead to it while it is running.

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Posted by keakar

Member since Jan 2017

30152 posts

Posted on 7/8/18 at 11:26 am to Hammertime

what you see is the clutch turning not the compressor, the compressor isnt running.

even a bad compressor would make the pressures have "some" change on each side.

and yes, when the compressor "is" running, it will have around 40-50 lbs pressure on the low side

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Posted by Hammertime

Will trade dowsing rod for titties

Member since Jan 2012

43030 posts

Posted on 7/10/18 at 10:03 am to Hammertime

7/10 Update:

I checked the static and running pressures. They are now the same for some reason. Both at 85/100. Ambient is around 90F. I guess that means the compressor is doing nothing, and it is possibly losing pressure, but how the frick did the low side get to 85psi, when it was only filled to 50?

My arm does not fit in the engine compartment, so I can't unplug the compressor to test electrical signal

This post was edited on 7/10/18 at 3:50 pm

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