electrical gauges reading change when turning on heater fan and A/C!

[mikyrc]

Hi guys I'm havving a little electrical problem and I don't know what can be the cause.

Everytime I turn the heater fan the electrical temp gauges I've installed does read around 5ºF more or so. It's more notticeable at max blow and A/C ON.
Well it seems that when there's something that places a high load to the electrical system the gauges read a bit off.

I tried to place a new ground wire from the batt terminal to a CAS bolt just in case there was a bad ground on the thermostat area but didn't help.

What can cause that and how to solve it?
A bad ground inside the cabin?

I would say the alternator is Ok as I've never got any ALT/brake warning light on the dash.


I've checked voltages with the engine NOT running and I got that:

Key on, ignition On, no fans working:
Batt voltage 12.36v
MMcd reported voltage 12v

Key on, ignition On, heater fan at max and A/C on (both radiator fans working):
Batt voltage (multimeter) 12.01v
MMCD reported voltage 11.7v

 

[Defiant]

Your alternator's in its last throes.

 

[mikyrc]

In the morning I get around 14.5v on the battery while engine is running, but as it warms up I see the voltage dropping. It ends at 13.7 (either on the alternator and batt) after driving for a while.

Does that mean the regulator is dying?
I just replaced the alternator bearings 1000miles ago also checked the brushes and were still long enough, also cleaned the rotor area where the brushes ride on.

Any way to check a spare alternator I have out of the car?

 

[KGB Pilot125]

In the morning I get around 14.5v on the battery while engine is running, but as it warms up I see the voltage dropping. It ends at 13.7 (either on the alternator and batt) after driving for a while.

Does that mean the regulator is dying?
I just replaced the alternator bearings 1000miles ago also checked the brushes and were still long enough, also cleaned the rotor area where the brushes ride on.

Any way to check a spare alternator I have out of the car?

Local parts store? CSK checks them on a machine that spins them and checks voltage and amperage and something else. I just had one tested yesterday.

 

[mikyrc]

Ok thanks, I'll ask around.

 

[knochgoon24]

Where are you tapping to get power for the gauges? Try a different power source or ground.

 

[mikyrc]

If I'm not wrong I get the +12 from the radio power wires and the ground from a bolt on a bracket on the radio area.