Poping fuses when ac controls are on

[Red Dragon Burb]

Hey everyone. I'm having a issue with the hvac in my 1990 suburban. The fuse keeps blowing left and right whenever I put the selector from off to any of the selections. I've replaced the blower motor, the ac compressor shut off relay, the heat and air blower motor resistor, replaced the ac defrost selector and the fan switch. The heat and vent setting worked up until yesterday and the ac was working for about 3months after it was charged. Now every setting blows the fuse. I've check the wires can't see anything rubbed or pinched or touching. It goes into the shop in a couple weeks. I'd like to save some money if possible. Any help is greatly appreciated.

 

[gmbellew]

I am not clear on when the issue started, when parts were replaced, or if they corrected the issue. But seems likely there is a short to ground somewhere with the blower motor wiring because the compressor doesn't kick on in the economy settings and the air direction controls are all vacuum based (like going from vent to heat). I think the "high" fan setting maybe uses a relay to bypass power going through the switch. You might see if you put the fan in high, and then turn on the system, if that still blows the fuse.

 

[Red Dragon Burb]

I bought the suburban in August. Heat was the only thing that worked at the time. Got the ac charged in September. And everything worked until October and the ac was popping the fuses. Replaced blower relay and resistor in April. Heat and vent still worked. Replaced fan switch and the ac defrost selector in April. Replaced blower motor of Thursday. I'll start checking off

 

[Snoots]

You need to buy yourself a DMM. You'll save yourself a lot of $$, headache and problems.

 

[Red Dragon Burb]

What's a dmm?

 

[Ricko1966]

Digital multi meter. Take a light socket for a 194 bulb,crimp a male spade connector on each of the wires to the socket,remove the fuse,place one spade connector in each contact for the fuse. Turn on the key and your HVAC now the light will stay lit,until you disconnect the offending component. Shake all the wires first in case ones rubbed bare and laying against metal.