tlaubner

I have a 1998 blazer and I just started having this problem. No matter which switch you change on the auto climate control, it will blow cold air for about 10 seconds and then switch to heat/vent for about 10 seconds and it continously switches back and forth between AC and heat/vent. Not sure if it's the climate control switch or something else.

MT-2500

besides electrical stuff there is a lot of vacuum controled stuff.
Make sure it has good engine vacuum to controls.
Any flashing lights or check engine ligts?
Any dead batterys or jump starts or work done on charging system or ac/heater?

Does the compresser clutch keep running when it does it?
Is it just the air flow change or is there a tempture change hot to cold and back to hot to?
Have you tryed a recalibrating on it?
Any body/ac/heater codes?

__________________
Remember proper testing gives us the answer to many problems.
MT

tlaubner

Any flashing lights or check engine lights?
No flashing lights.

Any dead batterys or jump starts or work done on charging system or ac/heater?
I replaced the battery almost 2 years ago. No jumpstarts. I had the AC charged early last year by the local Chevy dealership.

Does the compresser clutch keep running when it does it?
The compressor does kick on and off when it changes to AC from heat.

Is it just the air flow change or is there a tempture change hot to cold and back to hot to?
It goes back and forth between AC/heat/AC/heat/etc... Each cycle lasting approx 10 seconds. Even when the AC/heat is turned off. You can feel it coming out of the vents.

Have you tryed a recalibrating on it?
Not sure how to recalibrate it.

Any body/ac/heater codes?
None that I know of.

MT-2500

To recalibraste it.
Key off.
Remove the RDO/Batt fuse for a minute.
Install fuse and turn key on.
The actuator should cycle hot to cold.

If that does not help or the actuator does not move/cycle.
You will need to get a Havc/body capable scanner on it and check for codes and ac/heater operation.
Post back any codes.
MT

__________________
Remember proper testing gives us the answer to many problems.
MT

tlaubner

Removing that fuse did not do anything. I took it to a shop and they said there are no codes being reported. They did however say I have a have an intake gasket/vacuum leak. Would that cause a problem with the AC/heat?

MT-2500

Fix the vacuum leak and see what it does.
MT

__________________
Remember proper testing gives us the answer to many problems.
MT