ill try to make this quick
when i turn my heater on the voltage gauge drops significantly
while the truck is running. It has never done this before. If I rev the engine up the voltage will climb back to normal. The voltage will also drop when I turn the blower fan on. This leads me to belive the alt is failing. I disconnected the wire harness to the AC compressor and it stopped the voltage drop when I turn the heater on but the voltage still drops when I engage the blower. The voltage will drop when either of the two are turned on, the heater or the blower, so much that the engine stumbles and then recovers. Any advice?

thanks

Nick

 

The first thing you do is evaluate the charge system to see if it is performing properly.
If yes then there is a poor wire/ connection supplying the rest of the system.
The voltage going low will begin to affect the PWM operation hence the engine operation.

 

If I read right then I would have a amp draw test done on your heater motor.
Chances are it is drawing to many amps, due to age and or wear. It is possible that it is a bad high speed relay for your heater motor but if it is droping the engine rpm that much I would go for the heater motor first.

Feel it with the load against it, see if it warms up quick.
Also remember anytime the the defroster is turned on the AC compressor is as well. This would be even a larger amp draw on your system.

If I remember correct a heate motor on low should draw about 7amps total. Dont quote me tho.

 

yea my buddy had a smiliar problem with his truck turns out the alternator was failing which caused the power output to decrease significantly he got a new one put on and problem was solved not say that is your problem cuz it could be many things but i'd have your alt. checked first