Hey all
Having a little difficulty with the AC. It works great for as long as it's turned on but if you turn it off or shut down the truck and then turn it on again you never get it back...for like at least a day.

I haven't run into this before so wondering if anyone else has encountered this too?

I like AC and it's one of the few things I really must have.

Thanks
Steve

 

I suggest you try putting a can of refrigerant in and see what it does.
I haven't run in to that but mine was weak when I bought it. I eventually got a can with a connector on it that has a pressure gauge that can be connected to any other can of R134 refrigerant. Anyway I filled it up and it is cold now. It being a 94 it probably has leaks as I feel like I need to recharge it this year. I'm not ready to redo the whole system yet.

 

What do you have? 1994 or later? 1993 or earlier? It WILL make a difference. I suspect you have low refrigerant levels. There is a safety switch on your receiver/dryer. It's on the passenger side of the engine compartment near the firewall. It looks like a really big beer can with the aluminum refrigerant lines going to it. There is a small switch on the side.It just unplugs. Using a small piece of wire, jumper the two prongs inside. If your compressor starts working, it's low on refrigerant. This is where it makes a difference what year you have.In 1994, Dakotas went with R-134 refrigerant. Before that, they used R-12. It's available but good luck finding it. A lot of these have been converted to R-134.

IF you have an R-134 system, and IF it's just low on refrigerant, you can get cans with a gauge and use them to refill your system. I like to put a shot of dye in the system so if it's leaking, you can find it.

 

It's 94 with the 134A refrigerant and it cools just fine, it needs no refrigerant at all. I checked that at the beginning assuming it needed refrigerant but it needs nothing. I didn't use a professional gauge set but I have a decent charging hose with a reasonable gauge and it was without doubt sufficient. If it came to that I have a friend with gauges that I could have check it, if I can't figure it out I will hit him up for a check.

Compressor cycles as it should, temp down to 40F, very comfortable to run, but if you stop the truck and go into a store it won't work again when you come back out.

As a side note I haven't had any trouble finding R12. I typically hit several car swap meets during the year (this year the exception) and am able to round up a couple cans typically. It's never cheap, $10-$15 can but I can find it. I don't have any vehicles with R12 now (sold the last car a month ago) so I don't have any immediate need for more.

Steve

 

Don't these truck use vacuum to open and close doors in the hvac unit? I wonder if there isn't something making the door that lets air go over the cooling coil close or open.

 

Vac actuators are working fine, air is coming out where it's supposed to at the vents, and I don't think the temp control is vacuum although I could be wrong, but it feels like cable.

Besides, you're assuming that in the time it takes to fetch something inside a convenience store that the vacuum has bled out of the system enough to allow all the doors to return to default position..which is unlikely. That would suggest that there's a huge vacuum leak somewhere and I don't believe that's the case.

And further, the compressor isn't engaging.

Steve

 

The next time it fails to operate, jumper the switch connection on the receiver/dryer and see if it works then. It may be the safety switch is bad. They doon't fail often, but they can. At 26 years old, maybe yours has gone south. I'm not a fan of throwing parts at a problem, but they are reasonably cheap. It's also possible the relay is going bad from heat soak. That's easy to check by swapping it with another identical relay that you know works. If the problem moves, it's the relay.

As for R-12, I've got two cases. I've sold cans for as much as $35 but I think all the old systems have been converted and nobody needs it anymore.

 

Thanks for the tips, I will explore these two paths and see what I can find. TBH my first instinct was there was a switch problem somewhere.

I'm looking at a GMC motorhome in the future...I might need to procure a few cans of R12 to make the system operable...just don't know yet.

Steve

 

If it's an R12 system that already doesn't work, convert it to R134a.....

 

It's definitely R12, they made them from 1973-78. If the system is totally failed then if I can find new components to replace it and have the lines remade I would consider it converting to R134A.

Steve