Voltmeter and Idle Drop When AC On

[DryDog]

My X is turning 193. Driving with the AC on I can feel the engine brake when the compressor cycles on. If I am at a stop I have to give some gas or she'll stall. Other than a front-end problem (I'll post later) it runs great. Summer in MN just entered the 90's. Any ideas??? :fire:

 

[shamaal]

The EEC senses the A/C clutch coming on and kicks up the RPM to account for it. The compressor may be going bad and placing an unacceptable load or for some reason the EEC is not compensating.

 

[DryDog]

I'm home now, took some battery readings. Engine off 12.8V, engine on 14.4V. Everything on except AC 12.5V, lights dim but idle remains at 7 or 800.

With only AC on 14.4V but engine making death rattle.

 

[BrooklynBay]

Your voltage is never supposed to go to 12.5 when the engine is running. Check you battery terminals for corrosion. The IAC is supposed to compensate for the extra load, but if your voltage is too low, it won't work properly.

 

[expo5.0]

it will work down to 12.5 though just fine- i know mine does.

is the ac working properly otherwise?

I had a similar problem with a diffrent vehicle- and it turned out to be an out of round issue with the ac pulley itself.

 

[BrooklynBay]

AlDive had a similar problem when he installed those underdrive pulleys. He put on an overdrive pulley on the alternator from some company called UnderDog Performance for about $40, and it solved his low voltage at idle situation. Here is the link: http://www.explorerforum.com/forums/showthread.php?t=154990

 

[BrooklynBay]

This is a comparison of a regular pulley on the left, and an overdrive pulley on the right:

 

[DryDog]

5 years ago this month at 105K I had the compressor and associated crap replaced, and converted to R134. The 134 doesn't get as cold as the original stuff. But last summer and now it is not very cold at all. I charged it last
year with a kit from Checker but it didn't seem to make a difference.

 

[DryDog]

While chasing an overheating problem, I inadvertantly solved the AC problem. At least mostly. I replaced the belt, waterpump, and idler pulley. Volts still dip a bit with max AC at idle but, it drives OK.