A/C problem/question

[2000silvowner]

2000 5.3 silverado 80K miles recently purchased. Just added freon and the A/C compressor seems to be cycling on and off about every 3-5 seconds continously.

It gets cold only if you leave it on recycle mode so that as the compressor cycles it eventually cools the truck.

I read some other A/C posts and have a few questions, hopefully someone can answer.

1) this is a dumb one, is there a separate belt for the A/C or is it driven off of the main belt?

2) Why is the comprtessor cycling and how to fix? I was thinking the problem may be the presuure switch based on other emails. I was able to keep the compressor on by removing the connector from the low presuure switch and bridging with a paper clip so the compressor seems to function OK.

3) if it is the presuure switch can this be replaced without draining the A/C system?

Thanks for the help from a forum newbie.

This is the first Truck I have owned in 11 years and I am loving it issues and all.

[Vortec327]

Is the current pressure in the system correct? Ususally the compressor will cycle like this when pressure is too low....or possibly too high.

You mention you put in Freon....as in R12 ??.....your truck should be running R-134A.

[2000CAYukon]

Originally Posted by 2000silvowner

2000 5.3 silverado 80K miles recently purchased. Just added freon and the A/C compressor seems to be cycling on and off about every 3-5 seconds continously.

It gets cold only if you leave it on recycle mode so that as the compressor cycles it eventually cools the truck.

I read some other A/C posts and have a few questions, hopefully someone can answer.

1) this is a dumb one, is there a separate belt for the A/C or is it driven off of the main belt?

There is a separate belt for the a/c.

Originally Posted by 2000silvowner

2) Why is the comprtessor cycling and how to fix? I was thinking the problem may be the presuure switch based on other emails. I was able to keep the compressor on by removing the connector from the low presuure switch and bridging with a paper clip so the compressor seems to function OK.

If the compressor did not cycle, your evaporator would freeze and no air would flow thru it. The system is designed to cycle. This is due to the fact that the r134a is compressed and then expanded; therefore, the compressor cycles off to allow the r134a to accumulate before starting again.

Originally Posted by 2000silvowner

3) if it is the presuure switch can this be replaced without draining the A/C system?

The pressure switch can be removed/replaced without draining the system; however, that is usually only necessary when the compressor does not cycle or does not shut off due to a bad switch.

//2000CAYukon

[2000silvowner]

I added the 134A, don't know about the system pressure

[2000silvowner]

thanks for the info 200cayukon, I was hoping it would be a clearer reason. I knew that the compressor would cycle off during normal operation, but it should not switch on and off every 3-4 seconds

[2000CAYukon]

Originally Posted by 2000silvowner

thanks for the info 200cayukon, I was hoping it would be a clearer reason. I knew that the compressor would cycle off during normal operation, but it should not switch on and off every 3-4 seconds

Yes it should not be cycling every 3-4 seconds. I forget what is the normal cycling for the 2000. On my 90 K1500, it cycling on and off 6-8 times a minute (this is within factory specs).

I have the factory manuals at home and will look it up later.

Why did you add r134a? How much did you add? Overfilling could cause the compressor to cycle more often.

//2000CAYukon