Fan on with heat

[SHO93OFF]

I Know the cooling fan is supposed to come on with the A/c but everytime i turn on the heat or defrost my cooling fan comes on, i dont think this is normal, ideas? 93 mtx

 

[SHOZ123]

Defrost it should come on as the AC compressor is on too. Heat (Floor or vent) it should not.

 

[SHO93OFF]

relay control module ?

 

[93rev2sev]

Its supposed to come on with the heat, As stated. It helps dry the air as it defrosts the windows.

 

[SHO93OFF]

so the fan is supposed to come on with the a/c and heat and also defrost ?

 

[93rev2sev]

yupz.

 

[Axianator]

so the fan is supposed to come on with the a/c and heat and also defrost ?

Not quite. Read again what Paul said.

The climate control system should only activate your cooling fans under a mode where the A/C system is being utilized. In the case of the '89-'95 SHO, the A/C system is only used when the MAX A/C, PNL+FLR, FLR+DEF, and DEFROST modes have been selected. Occasionally, the AUTO mode will also activate the A/C system.

 

[SHOZ123]

And at speeds under 35 IIRC.