I am going to look at a 1988 7.3 IDI (non-turbo) tomorrow with 57K original miles, asking $12K. The seller is about 3 hours away and is listing for a person he knows (seem like this is his side gig). He is a car guy as far as I can tell from his FB page and does have a garage but I am not sure that is his full-time job. He has been extremely communicative, answered all the questions I have had, even fixed a few things, replaced both batteries, replaced the cracked windshield, and sent tons of pictures and videos. The one issue he says the truck has is that the AC head unit is stuck on the window vent so he cannot test AC. He did recharge it; it has the upgraded fitting for the R134.

My question is what the problem could be and what is an estimate to get something like that repaired. I can do the general maintenance work on the vehicle, but I would be bringing this to a shop to fix...unless there is some possible easy fix, but I am not sure anything is easy with the vacuum lines or I would have the right tools. Any suggestions would be appreciated.

 

Since you admitted that you would take the truck to a shop to have the AC fixed, I'd think it would at least be several hundred dollars to fix. Are you willing to pay that right after buying the truck?

More importantly, are you meeting the current owner at his home, or in town at a public place (i.e. police station, grocery store, etc.)? When you start the truck you need to make sure the truck is cold. Lift the hood and check the engine. If it's cold you can test the condition of the glow plugs.

BTW, is the truck a crew or super cab? Is it 4x4?

 

It is a regular cab 4x4, meeting him at his shop and I am sure if I ask, he will leave it cold from the previous night. It will be about 35-40 degrees overnight where he is.

The premise for my questing, as best i can get an answer from anyone not seeing or testing it of course is to come up with a reasonable offer, so I will estimate the repair cost and deduct that from my offer, at least that is the idea

 

Something is fishy about this... I'm not sure what "window vent" means? Defrost setting will shoot some air out the window vents, but that is NOT a setting by itself. My '88 had a push button to turn on the AC compressor. It's been a while since I was in the truck, but I believe it had a lever that controlled where the air went, and was cable controlled. So the AC could go anywhere you want if you pushed the button in. However the AC was I think always broken in that truck so... *shrug*

Also, as far as I know, you can't recharge the AC if its not running. So how did he recharge it?

 

Window vent I wonder if they were trying to say defrost? Not sure on that year truck if the doors were controlled by vacuum or not. Often on a vacuum control system the default fail mode is defrost. If vacuum it could be as simple as a hose disconnected or vacuum pump failure. The compressor could have been running even if you could not change air flow to different places. It is also possible to hot wire the compressor for charging. Just not enough information to really know what is going on at this point. As to OP question on cost, at this point $50.00 to $1000.00 since we really do not know what is wrong.

 

Got some updates, and it does seem like it could be a hose, but we shall see. The compressor indeed was running, and it is just that the air flow could not be changed. This picture below is the head unit the truck had (image from an eBay posting), so by window vent, I just meant VENT position.

I made an offer that took the possible $1K into consideration (and then some) which he accepted, so I will head there tomorrow to hopefully bring it home if everything else we have been discussing over the last week turns out to be accurate. I have also told him to not start the truck tomorrow so we can get a good cold start and test the glow plugs. He confirmed he has what is needed to do this with me there, though he has already done it when prepping for sale. The low there will only be 48 and by the time I arrive it will be closer to 62 but we don't get much cooler than that in Phoenix so that will have to do for now.

Appreciate the answers, and I will follow up once I have more information if anyone is interested.

 

it could be a bad selector cable, or a vacuum leak.
the only way to tell is see if that unit is cable or vacuum controlled.
my trucks all had the other style controls with push button to turn ac compressor on, and they were vacuum controlled

 

I picked up the truck Friday, de=rove it 3 hours home and then out for some fun yesterday. No need for air or heat here in AZ at the moment, but that will certainly change so I will have this issue looked at in the coming weeks, thanks for the tips

 

From the rust belt, I can say, Gosh...that's nice.

 

Quick update if anyone is actually interested, final purchase price was $10K. Truck is running flawlessly so far...for the 1K miles I have driven it. Cold start is not an issue here in Phoenix, but it does start right (maybe 5 seconds of cranking) up at 35 after sitting a couple of days, then starts up instantly once she has run once for the day. Turns out when I went to pick it up there was a gear vendor under/overdrive installed, but they did not know anything about it, and it was not working as far as they knew. I called GV and with some pointers from them, a drain and refill of the ATF which was very low, I was able to determine it definitely works as intended, but the electronics were the issue. So, for $475 they have sent me the most recent generation controller and retro fit instructions and that should make it fully functional, I am please about that for sure. Changed out all the fluids, oil, trans, diff, coolant and replaces all seals, though it wasn't leaking before. E brake was not working so realigned the drums and that is functioning as it should now as well. I don't know what 18-year-old put the stereo into this thing but there are two amps and two subs behind the back seat that are like a back massager if I turn it up that loud...it's truly reminiscent of life in 1988 when I tune into Hair Nation

A/C will be next, but not for another month.

 

Excellent! A GV unit is quite a find.