90 burban acc/heat fuse blows

[1990burb]

alright guys so this is my first post here on this awesome forum so bare with me please. so yesterday i charged up the ac in my truck and everything was good. nice cold ac. but the issue arose once i started to drive the truck down the road. so once i am moving the acc/heater fuse blows. along with the blower no longer functioning the speedo is also on that circuit and no longer works as well. so i replaced the fuse and as long as the truck is parked the ac works great no fuse blown. and same with the speedo as long as the air is off while in motion. any ideas of where i could be looking to solve this little conundrum? i sure would like to enjoy the ac while driving not just parked lol. any input and/or suggestions would be greatly appreciated. thanks in advance

 

[89Suburban]

Is this the front ac fan or rear fan? Does changing the fan speed make a difference? Does it happen at all fan speeds? Does it only do it with the AC on? What about when the heat is on? Sounds like a intermittent short or blower motor is pulling too much amperage. You can also pull the blower motor and the resistor out of the blower housing to look for debris causing an issue.

Here is some troubleshooting stuff:

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

You must be registered for see images

 

[1990burb]

my burb only has front ac no rear. I'm not sure if it does it with only the heater on i will check that out here in a few. changing the fan speed doesn't make a difference any speed blows the fuse if the vehicle is in motion while the blower is operating with the ac on thank you for the diagrams and trouble shooting guides i will put those to use today and get back. thanks again for the input

 

[1990burb]

ok so a little update. the fuse only blows when the ac is on and the truck is moving. does not blow if the truck is parked. and does not blow if the heater or vent is on rather it is moving or parked. so i am thinking the problem has to lie in the ac circuit. i read something about the little diode on the connector for the ac clutch. it was suggested that i should remove that diode. but I'm figuring it was there for a reason and wanted to check here if anyone had heard of that or not and what the possible outcomes may be. once again thanks for taking the time to review my post and i look forward to any and all input.

 

[350runner]

Try just unplugging the connector to the compressor.

 

[chengny]

Try just unplugging the connector to the compressor.

At the firewall. That will eliminate any shorts in the entire run (from the firewall connector, down on to the engine, all along the valve cover and up to the compressor clutch):

You must be registered for see images attach

You must be registered for see images attach

 

[350runner]

True, they both sound like good ideas.