HELP: New A/C Compressor not coming on

[wiseman]

I have installed a brand spanking new compressor with a new dryer and the compressor is not coming on. I have checked the fuse under the dash, changed the relay on the fender, vacuumed the system down (maintained -26Hg), and made sure everything is connected. I also have the paper clip in the pressure sensor, still NO compressor coming on.

P.s. ---I noticed that I have no power on th connector that plugs into the front of the compressor (the flat, black one) that has 2 prongs? Should have power on this connector?

I am working on the car as I type this message, any input is appreciated, thanks

 

[Nick Micale]

Is the small red connector on the back side of the compressor plugged in?

 

[huntsg]

That connector on the front of the compressor will fit both ways (at least on mine it does) but it will only work if plugged in correctly.

 

[GNRick]

The green wire from the low pressure switch on the accumulator to the compressor might have broken. Try splicing in a new wire. This happened on my car.

 

[wiseman]

Thanks guys! The male connector (coming from cars harness was seated properly. And I noticed that I had a connector by the blower that wasn't connected. It was hiding down in the corner. B/w these 2 items, my compressor instantly came on. Hadn't had the a/c components in for about 4 yrs and forgot about that plug. Thanks everyone!




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[wiseman]

I have 2 more issues...

1. The blower isn't blowing when I switch the fan speed to "high". Is it the actual controller or something else that I may need to change?

2. The air wasnt blowing out the center vents, it was mostly blowing out the floor or upper dash vents. I had to go under the dash and move the blend door by hand to get the air to blow thru the center vents, and some air was still coming thru the floor vents as though it was on "bi-level". Any thoughts of what I could do to get it to blow out the center vents?

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[wiseman]

Hello,
I checking pressures and this is what my manifold gauges are reading. My questions are..... which "Pressure Scales" on the gauge sets should I be looking at for the low and high side pressures?

For example: the instructions state that the low side pressure should have a range of 24-30 on the low side and 130-190 on the high side.

1.) Is the low side range reading of 24-30 supposed to read on the blue gauge from the "outer-most scale?"
i.e., (the R134a scale from -40 to 35 circled pink) or should it be read from the "inner scale" (Classe 1.6 scale from 30 to 120psi, circled yellow)

2.) I would assume that the high side range of 130-190 is read on the red gauge from the "inner-most scale" (Classe 1.6 scale from 0 to 500psi, circled pink), correct?

Presently, the gauges read about 60psi on the low side, and out 390psi on the high side. Its about 98 degrees with 48% humidity currently in Houston.

 

[GN owner]

The low side and high side pressures are too high. Make sure that the cooling fans are running and that there are no obstructions to air flow through the condensor. The other possibility is that the system is overcharged with refrigerant.

 

[jimmymack87gn]

Agree with above... about air delivery issue this is the default position for no vacuum. Check high blow relay for no high speed

 

[jimmymack87gn]

High speed relay located behind the dryer with 2 seven mm screws securing it.

 

[RmvBfrFlght]

The area of the gauges circled in pink is where to read them. That is the line pressure. The area of the gauges marked in yellow are just a reference. It will be the temperature of that particular refrigerant at that pressure.

When checking the pressures the doors should be open, the A/C blower on high, and the engine at 2000 RPM. Note that his info is from a '92 Camaro factory service manual, but shouldn't be much different from a Buick.

Ay 100* F ambient, and 50% humidity (close to what you posted), the low side should be at 40 psi, with the high side at 350 psi. This is for R12, if using R134 they are going to be a little different (higher?).

Center duct outlet temperature should be about 68* F. For the best performance consider filling the system with ES-12a

RemoveBeforeFlight

 

[wiseman]

My system was bone dry and I have but 3.5 cans (12oz) of Freon into the system. The cooling fans are turning on and off as normal from what I can tell.

So my pressures are high even though the ambient temp. Outside was 98 degrees?

I just noticed this, the low pressure line (the larger diameter one) is freezing cold, but the low pressure line (smaller one) doesn't show any wetness on the pipe. Is this a sign of a blockage in the high pressure line? I am getting cold air through the vents. Are both supposed to be frosty?

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[robzombie]

High side should be hot low side should be cold.

Pressures will also vary with outside temps. Outside temps will dictate what you will have for pressures and inside temps.

I typically keep my low side pressures between 40/45 and that is considered a little high.

60 is way to high and while it maybe working for you now, you will destroy that compressor if you continue to run those pressures.

Even with the temp/humidity you have in this post you shouldn't be over 45/50.

Try it in the morning when the temps are 20* cooler and take another reading and report back what you have.

 

[wiseman]

Agree with above... about air delivery issue this is the default position for no vacuum. Check high blow relay for no high speed

I got a new blower relay, and the fan works on the high setting now, thanks....

 

[wiseman]

High side should be hot low side should be cold.

Pressures will also vary with outside temps. Outside temps will dictate what you will have for pressures and inside temps.

I typically keep my low side pressures between 40/45 and that is considered a little high.

60 is way to high and while it maybe working for you now, you will destroy that compressor if you continue to run those pressures.

Even with the temp/humidity you have in this post you shouldn't be over 45/50.

Try it in the morning when the temps are 20* cooler and take another reading and report back what you have.

Ok, so the low side line isn't supposed to be cold......that's good news (I guess) so that I don't have to open the system and loose the new freon.

I will check my pressures again in the morning in some cooler temps as you suggested and let you know what I get.

Semi-Update:

1. I started the car again and the cooling fans always turn on with the key "on" and remain on for a while after the key is turned "off".

 

[robzombie]

Ok, so the low side line isn't supposed to be cold.

Low side should be cold, The R/Dryer should be sweating like a two dollar crack whore on a Saturday night and be very cold to the touch, the R/D not the crack whore.

 

[wiseman]

Low side should be cold, The R/Dryer should be sweating like a two dollar crack whore on a Saturday night and be very cold to the touch, the R/D not the crack whore.[/quote

Ok, cranked it and yes your are right the low pressure side "is cold and sweating like a crack whore on sat. Night" LOL!

Here is what the gauges are reading (see attached). It's about 45psi on the low side and 300 on the high side.

Temperature here right now Is 88degrees with 60% humidity.





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[wiseman]

Ok, cranked it and yes your are right the low pressure side "is cold and sweating like a crack whore on sat. Night" LOL!

Here is what the gauges are reading (see attached). It's about 45psi on the low side and 300 on the high side. I never stated before, but I am using R134a refrigerant.

Temperature when I was measuring was 88 degrees with 60% humidity.

 

[wiseman]

I checked the A/C section in the TR service manual it is stated that the low.pressure reading should be 30-35psi.

I let out some refrigerant and got the pressures down to 33psi on the low side, the high side was reading about 295psi. But now, the A/c is much warmer. The temp. Here is now 90 degrees with 59% humidity and I know that it is under filled b/c I had 3.5 cans of Freon in the before which was exact. I just removed some to get the pressures down so I know that I am low.


Here is a r134 chart that I found, that I thought was right, but according to what I am understanding from this post, the pressures in this chart are too high for our systems, right?


http://www.idqusa.com/faqs.php?faq=74&faq_id=74&category_id=18


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[GNRick]

I once checked out a book from the local library on a/c repair. However I don't remember enough to help you.....except for recommending your local library. The book also prepared you for the ASE exam. It covered how to charge the a/c, how to read the gauges, types of freon, etc.