If you unplug the fan switch fan will run all the time diffrent plugs I can give you a part number for the switch if you have a good napa they can sometimes cross the number over
i always thought the high side switch controlled the fan.i have noticed on pete's and k.w. (387/t2000)that there are 3 switches on the expansion valve.could you please explain what the 3 do.thanks.
Your truck either has expansion valve or orfice tube if it has an orfice tube it will have a alum. accumulator on drivers side firewall. The compressor is cycled by a low pressure cycling switch witch is a gray colored switch by the firewall. If you overcharge this type of system the compressor will not shut off unless you really overcharge it the the high pressure protection switch will shut the compressor off. This will make all the lines ice up.
I've done a little A/C work on my '03 379, well,, a lot of work. I did some repairs but the system just wouldn't take refrigerant at any reasonable rate. Come to find out, the orifice tube had never been replaced, thereby causing a restriction. On mine, it's in the lowside ?? line right where the hardline enters the firewall, BE CAREFUL when pulling it out as it might splinter being as it's plastic. I'd like to say it's kind of a filter for debris in the system. Mine was gummed up but fortunately no shrapnel. Swapped it out and the refridgerant practically fell into the system. It's basically a tube with slots and very fine screen that all the refridgerant must pass through. I hope the gurus here will back me in that, whenever the system is opened replace at the very least, orifice tube, accumulator/reciever-dryer and ANYTHING questionable. When you or the tech pulls the system down (vacuum) you don't want, "think we should've replaced such and such?"
I installed a brand new dryer and orifice on my daughters Ford Tauras, vacuumed it down and charged it and that car had some awesome cole cold hard blowing air. The car had set for several years and we got it for 300 dollars because it was thought to have had a bad engine. Turns out it had faabs issues that wouldnt let it run.( Key/antitheft) The AC ran for 2 months perfectly until the bearing on the compressor shaft started squeaking and eventually locked up. She was out of town visiting friends and got the compressor replaced by her friends mechanic. Just for information he only replaced the compressor vacuumed it down and charged it and it worked just as well as it had before without replacing the 2month old dryer or orifice. So I guess it depends how new some of the components are. And since it was a bearing failure instead of a compressor failure, no contaminants were passed through the system.
