A/C and Fuse Panel Puzzle

[broncojohnny]

I'm trying to trace my A/C issues - light comes on but clutch not engaging and no cold air. I know it was getting warmer last summer so it may be out of freon. I took a look at the fuse panel which supposedly has a fuse for "air conditioner switches and clutch" according to the Haynes manual. It lists it as a 15 amp fuse but the sketch in the book shows it to be a 10 amp fuse. Mine's a 10. I saw a pic online and it was a 10. I pulled a few fuses just to see and some of the components work without the corresponding fuse in!? Some don't which is what I would expect.
Any got ideas about where I should looking or what I should be trying ?

 

[L\Bronco]

Hey BroncoJohnny
Not sure which Bronco you have, but most run an orifice tube system.
If you look at the small tank on the firewall where the hoses come out of the evaporator case, there should be a sensor on it with 2 wires going into it. Unplug it and jump the 2wires together with a paperclip or jumper wire with the engine running. If the compressor starts with the jumper in, you are out of refrigerant, or the low press sensor has failed. (Likely low charge)
If it wont run with a jumper installed, the clutch control circuit has an issue.
Hope that helps
Cheers

 

[broncojohnny]

Hey BroncoJohnny
Not sure which Bronco you have, but most run an orifice tube system.
If you look at the small tank on the firewall where the hoses come out of the evaporator case, there should be a sensor on it with 2 wires going into it. Unplug it and jump the 2wires together with a paperclip or jumper wire with the engine running. If the compressor starts with the jumper in, you are out of refrigerant, or the low press sensor has failed. (Likely low charge)
If it wont run with a jumper installed, the clutch control circuit has an issue.
Hope that helps
Cheers

It's an '89 B2.
So the sensor doesn't allow the compressor to come on if it's low on freon? If that is so it would make sense as It's already been acting like it's low or out.
Any thoughts on the fuses and why stuff runs with the fuse pulled out? Does that A/C clutch fuse do anything?

 

[L\Bronco]

Correct about the sensor, it shuts off the comressor when the pressure is below about 25ish psi. It controls the temp that way plus prevents the compressor from running when empty.
Since you experienced a loss of cooling, it would suggest a low charge.
Jumping that circuit will prove it.
Also, if you are out of refrigerant, there is likely a leak, depending on where you live, it may be difficult to get it charged without a leak check. (Environmental laws and such)

As far as the fuses go, I would guess that your fuse panel diagram is inaccurate, look online for a free PDF of an owners manual for your truck, it will be correct in there.
The only way a circuit can work without the fuse is the fuse wasnt for that circuit, the circuit has been rewired, or there is a very weird short in the harness. The only likely option is the info is incorrect.
Hope that helps
Cheers

 

[wyo58]

I believe that the 89 had R12 unless it has been converted to R134A. There is probably now way your going to find R12, so hopefully it has been converted. Also R134A has a tendency to find it's way out of most flexible lines. It is getting harder to find R134A these days as well.