idle drop w/ a/c

[philly5eagle]

Idles fine without a/c on. If i turn a/c on the rpms drop to about 500. I have read about idle surge etc but I dont have that. Idle is at 750, sometimes to 800 but pretty much steady, even steady at 500 with a/c on. I cked the ohms on the isc and all read 32. I unplugged the a/c comp. to see what happens looks like the rpms drop for a second and then back to 750. Question is, does the isc move due to the load on the engine or due to an electrical signal that tells it the a/c has come on. I have looked in multiple places and heard it both ways and I'm trying to find out which is correct b/c that may help narrow down the problem. If my compressor is bad then may be putting too much of a load on the engine. Or maybe something else. I must mention that this problem started around the same time I had a problem with the alternator . I was driving at night and the lights went dim etc. Drove it as far as I could to get it somewhere to park and the next day picked up a alt from the junkyard just to get by. Is it possible that the alt is not putting out enough or is something else fried somewhere. I read a few people having the exact same problem but never an answer to the problem. they have replaced alt, isc, ecu etc and never fixed problem.

 

[CCR17Darcy]

Does the A/C still blow out cold air? It is pretty normal to have the idle be effected by turning on the A/C. Afterall, it's more work for the engine. If the thing is still putting out cold air, and the car doesn't stall, I'm not sure I'd be to concerned about it. But, that's just my opinion, which is most likely incorrect. (but it may not be).

 

[ddavisaf]

Don't worry to much about it at this point. AC is ran off of a belt that is inactive while the compresser is inactive. When it's on it's having to spin an extra pulley with an added load and will drop your rpms accordingly.

If it's bothering you then you should take it out. It'll free up around 40 pounds. Plus, you won't have to worry about it decreasing performance.

 

[philly5eagle]

Everything I have read has stated that the isc is to bump up the idle by about 200 rpm to adjust for the load of the a/c. That way your rpms do not drop. My car was increasing in idle like it should until I had the alternator go out. Now I'm having all sorts of problems. Idle wont go up w/ a/c on. Lights on dash and headlights will surge brighter for a few seconds every once in a while, fan in car will blow out more air for a few seconds. I'm thinking maybe it fried the battery or another wire somewhere that I can't track down like a ground wire.

 

[philly5eagle]

Also last night I was playing with the a/c and noticed the driver side fan was not coming on which I believe is the fan for the a/c. So it may not be getting a signal either. The a/c compressor does come on and cool though with is strange.
Is the driver side fan the a/c fan? And where does it get its signal from?

 

[cuban11182]

it gets its signal from the relay in the fuse/relay box in front of the driver strut tower. one of the two silver ones

 

[philly5eagle]

Thanks for the reply
If the signal goes to the a/c fan from the relay, then where does the signal come from to the relay? I'm trying to figure out if the fact that the fan isn't working is related to the idle not going up when the a/c is turned on.

 

[philly5eagle]

Update. I tried replacing the a/c controller that is located above glove box and that made no change. I also replaced alt and battery and no change. Tested isc again and ohms still within range. Ecu shows not sign of damage or strange smell. A/C will come on when butten is pressed and blow cool but idle drops unstead of going up like it is supposed to. However I'm not using it as the a/c fan will not come on either. I cked the plug at the a/c fan and one of the pins on on the connector and the plug it goes into were both toasted??? So I replaced both ends and still fan doesn't come on. I replaced all relays and fuses that were located in the fuse box over the drivers side shock tower and still no change. Is it poss that the a/c fan and the idle not bumping up could be related even though the a/c compressor comes on?

 

[ddavisaf]

Try to hotwire the fan so that it comes on. This is to see if the fan itself is burnt up. Or, just switch the fans for temporary purposes to test the theory.

 

[philly5eagle]

Thanks, I'll ck it out.

 

[philly5eagle]

Ok, so it's hot again and I'm back to having to use the a/c. Still the same problem as last year. I have never read where anyone who has the same problem has come up with an answer. Idle drops and runs too low when a/c comes on. From all the reading this is not normal. Idle is supposed to bump up to compensate for the a/c load. Cked isc and it is good per specs. A/C fan in engine compartment won't come on either. However, a/c blows cold.
Anyone??
It's driving me nuts, and I know others have had the same problem on here but no solutions, other than a few who just sold their cars!
Thanks