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99 Tahoe A/C blowing hot

chosen1608

By chosen1608
in Ask A GM Technician

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chosen1608 New Member

chosen1608

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I have a 99 OBS Z71 Tahoe and lately the A/C won't blow cold. I had it recharged last April. When I look under the hood, I can see/hear the compressor come on but it cycles very fast (on 3 secs, off 10 secs). I do not know where the low side port is to check the readings. I see a manifold towards the front of the engine that has 2 ports. One is vertical and one is horizontal, pointing towards the front. Is this the low side port? Any help would be greatly appreciated.

superman072000 Enthusiast

superman072000

Posted
Posted
I have a 99 OBS Z71 Tahoe and lately the A/C won't blow cold. I had it recharged last April. When I look under the hood, I can see/hear the compressor come on but it cycles very fast (on 3 secs, off 10 secs). I do not know where the low side port is to check the readings. I see a manifold towards the front of the engine that has 2 ports. One is vertical and one is horizontal, pointing towards the front. Is this the low side port? Any help would be greatly appreciated.

 

Chevy Compressors SUCK! You will have to replace the compressor. Same thing happened to my 04 silverado only a little sooner.

ZZ327 Senior Enthusiast

ZZ327

Posted
Posted

you probably have a leak somewhere, The compressor is cycling because youre low on freon. The low side port is the larger stub it might have a Blue colored cap on it.

chosen1608 New Member

chosen1608

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I got no blue caps. Just the two black caps covering the two ports on top of the compressor. One sticks straight up and the other faces forward. Can anyone tell me where the high and low ports are?

ZZ327 Senior Enthusiast

ZZ327

Posted
Posted

Unless its different than normal, I think the LOW HIGH taps are on the AC lines themselves, Your looking at the hose connections to the compressor.

 

one port should be physically bigger than the other, that bigger one is your low side.

 

Otherwise trace the lines leaving the compressor, one will be entering the the heat exchanger AC box through the firewall , the one that is leaving the heat exchanger box and running directly back to the compressor is the low side.

 

If Im remember my refrigeration class right, at the compressor connection one line is towards the center of the back side of the compressor this is the HIGH side line. The offset one will be the low side

 

If you have a guage, check the pressure you have it will tell you what is high and low. Always charge your low side to about 45 PSI with car Running!

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