How to Diagnose a system.
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Joined: Aug 2009
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How to Diagnose a system.
This is my first truck and i just bought it yesterday, I'm not a mechanic, but fairly mechanically inclined and a quick learner. I've searched this forum over, but have not found the answer i'm looking for.
Please explain to me in great detail what to look for.
The Truck: 94 F-150 XLT 5-speed 300-I6
The Problem: AC blowing hot air.
What I've done: Start the truck, look at the compressor, (looks like it's spinning to me), engage the AC, look again (yep the pully on the compressor is still spinning).
And that's pretty much where i stopped, cause i don't know what i'm looking for, should i be seeing it not spin if it where seized, and whats next on the list to check.
I assume that it's not seized at this point and it must be something else, like a control, keeping it from working. Any help would be great.
Please explain to me in great detail what to look for.
The Truck: 94 F-150 XLT 5-speed 300-I6
The Problem: AC blowing hot air.
What I've done: Start the truck, look at the compressor, (looks like it's spinning to me), engage the AC, look again (yep the pully on the compressor is still spinning).
And that's pretty much where i stopped, cause i don't know what i'm looking for, should i be seeing it not spin if it where seized, and whats next on the list to check.
I assume that it's not seized at this point and it must be something else, like a control, keeping it from working. Any help would be great.
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
Likes: 5
From: Lorain County, Ohio
The compressor pulley turns whenever the engine is running. Look closely at the front face of the clutch and see if it is spinning with the pulley when the AC is turned on.
When you say it "blows hot air", is it ambient temp air or does it seem to be heated by the heater?
Follow the AC lines back to the firewall on the passenger side. Feel the pipes right where they go into the firewall. They should both be cold if the system is working. If the compressor is actually running, at least the small lower pipe will be cold or cool.
Post back with what you find.
When you say it "blows hot air", is it ambient temp air or does it seem to be heated by the heater?
Follow the AC lines back to the firewall on the passenger side. Feel the pipes right where they go into the firewall. They should both be cold if the system is working. If the compressor is actually running, at least the small lower pipe will be cold or cool.
Post back with what you find.
