benjacob

Hope ya all had a great Christmas.

Thank you to those of you, including Mack1, that assisted me with my alternator/electrical anomoly. After having taken the alternator out during my engine head overhaul, and having reinstalled it, my volt-gauge reads 14.5+ volts!!! Yesssssssss, problem solved. Thank you. (the post on the back side was rusty, probably a bad connection).

NOW, I have a new problem, and I'm not sure if it is electrical or not. I have reassembled the engine and all connections, hoses, links, etc.. The engine started up very nicely, and have test driven the truck. It is running sweeeeeeeeet!

The problem, and only problem I NOW have is that the AC is not kicking on, AND, I have NO air coming out of the upper vents (the vents in the dash that you can adjust). I have control of the defroster & foot vents. After having run the truck with the AC switched on, the AC came on after 5 minutes, and it seemed that it was working fine (still no upper vents). Then, I came back to the truck several hours later, and now the AC is not working again (in other words, the clutch is not engaging). The electrical connector is secured to the AC, and have reconnected it, checked the connections, wiggles it, etc., but no luck. Again, any suggestions here are more than appreciated.

Happy New Year!!!

mack1

Hi Ben and welcome back,

That was good news on your alternator.

Not too sure what the problem with the vent control could be except vacuum hoses under the dash. I don't find anything on the electrical prints that indicate any other kind of control for them. I had my lower dash apart sometime ago for instrument pannel work, and just don't recall what the controls for the vent system looked like. Took pictures but can't find them now.

I have attached below the print for the airconditioner compressor. The circuit on the right (fuse 6) includes the ac low pressure and high pressure cutout switches also a bleed resistor. The circuit then reports to the VCM (PCM/Computer) which engages the compressor clutch on the left side of the print if all conditions are met. It, of course, knows when the ignition switch is on and the engine is running. I think the high pressure switch is shown wrong in the print. I think it should be normally closed until over pressure causes it to open, stopping the compressor. The low pressure switch is opened until you charge the system with freon. If the system is low on freon, this is the switch that causes the compressor to cycle on and off at fairly short intervals. The switch is located on the low pressure line near the canister before going into the evaperator section of the unit.
You'll have to search for the high pressure switch, I haven't had a need to locate it on my vehicle.

The other print is for the instrument pannel and item 2 points to the resistor shown on the electrical print in case you need to check it.

Best of luck,
Mack1

Airconditioner 004a.jpg

Airconditioner 001a.jpg

cardoc

Try shorting the low pressure switch termials together with a paper clip.If the compressor runs at that point you know it's low on charge.If not you need to jump into the wiring diagram with a volt meter.
The vent problem sounds like the vacuum line problem.
Good luck,Cardoc

BUDFAN8

look for a vacuum line coming from the firewall that will be your problem of why the dash vents arent working. as far as the compressor ill let the others handle that i hate wiring trouble.


Bud