[93stockerstang]

anybody got any ideas what to check? heat blows ,air is out, either way the blower causes rpms to jumps a couple of hundred meaning it revs up and down at idle without the blower she runs great so its not the idle air sensor.

[b_chandler]

The EEC is set up to compensate for the additional load of a working air conditioning compressor. Since yours isn't functional, it kinda throws it off balance. Nothing wrong with the car other than your A/C is broke

Oh and just because you have the heat on and not the a/c doesn't mean the compressor isn't supposed to be on.

[93stockerstang]

I meant when you turn the blower on or just switch the control switch to any of the on positions it drains the motor, drops the volt meter down 2-3 volts and lugs the motor. I took the ac out so that is not a factor. replaced the belt, bypassing the a/c pulley.

[sleeper_inc]

Just pull the AC belt off and it should be fine

[b_chandler]

He's already bypassed the A/C compressor Sleeper.

I can't put my finger on this one. With the compressor gone, it should idle up when you turn the selector switch from OFF to any other position or kick the blower on, the fan should come on as well.

Your fan works right?
You know, I'm thinking there might be a vacuum issue. You said it didn't matter whether you turned the blower on or the A/C selector on. You're right. The blower won't kick on unless the A/C selector is not in the OFF position. That makes me move electrical issues to the back burner for a minute. Check vacuum lines going to the A/C box. I wouldn't cap and plug them, you may need them this winter for heat and defrost. But you will need to inspect them for rot and make any repairs. If you want, you can cap them off and see if it improves then you'll know without spending alot of time or money.

A little vacuum leak would make the motor drop and hunt around for proper idle.

[sleeper_inc]

Sorry, didn't read it close enough

[93stockerstang]

Lets try this one more time idle jumps up rpms rise then go back to normal every few seconds with blower turned on, I just wanted to clarify the question . Any ideas would help?? Possibly 02 sensor what do you think without the blower it idles perfect.

[krk105]

It sounds like a vacuum issue. The heater and A/C controls use a vacuum system to open and close gates in the duct work of the heating and cooling system and requires a constant vacuum when in use to operate normally open or closed gates in the duct work.

Additionally when in use this would require more vacuum for the entire system to function correctly. A leak in a line would drop the vacuum pressure in the entire vacuum system, which is linked to the Idle Air Control valve and EGR valve to name a few.

Any dry-rotted or cracked hoses need to be replaced. Check fittings and joints for proper seal. Silcone sealant can be used to help seal up around joints and fittings.