I am sick of my inadequate dealer air in my 77 F250. I can get the vent temps down to 40 degrees, but the darn thing doesn't put out enough air to cool the cab down. We live in 100 plus degree desert and on short trips the cab just starts to cool down when you have arrived at your destination.

I talked with Tom at Nostalgic Air and he stated that even their smallest under-dash unit blows icicles, but they have to be located under the glove box. He states that if you mount them over the hump you have to tilt them at 60 plus degree angle and they blow water. It would be a major inconvenience to mount the thing that far away from the driver.

Has anyone on here had any experience mounting one of these units in the 1973 to 79 trucks? How about pulling the factory heater completely out and getting the heat and cool model under-dash unit? I would hate to lose the defrost function, but I would consider doing this if it would get me more room to mount the unit over the hump.

 

Have you ever opened up the evaporator case and cleaned it? There is probably 31 years of crap plastered on the evaporator, blocking the airflow. The factory AC in these trucks normally moves a ton of air.
Try that before you reinvent the wheel. With the underdash units, you lose dehumidification when on defrost. It doesn't sound important until you don't have it, trust me. You may be spending a lot of money to bypass a cheap fix.

 

Thanks for the suggestion, but this is not factory air. It is dealer air and they are notorious for their inefficiency. Also I have had it apart and thoroughly cleaned and resealed it. The darn thing will not move very much air. This thing is so inefficient that the center vent temps drop ten degrees from low to high fan speed. I really don't want one of those bulky units hanging out from under the dash, so I have tried everything to get this thing to work. All efforts have failed.

 

Aaahh, I missed the "dealer installed" part. You're right, those suck swamp water.
Take a look at the vehicle specific kits and universal evaporators at Automotive Air Conditioning Parts & Equipment - ACKITS.COM. I wasn't able to find a specific heater/AC unit. Surely someone makes one?

Replacing the evaporator/blower asy. would help, but I wonder if the rest of the system is up to the task. A big part of the trouble with old dealer add ons was the crappy condenser. You might be better off with a whole system.

 

Another good suggestion, but "already been there done that."

I replaced the condenser with the largest Parallel Flow I could put on it. Also replaced all of the hoses with barrier hoses, new drier, new compressor, all connectors are now o-ring with the exception of the evaporator.

I left the original evaporator in there to retain the stock look, but I need to be able to cool the darn truck down. Right now my only alternative is the under-dash unit unless I can somehow find a larger evaporator coil to put in my box.

And yes they do make an under-dash unit that has a heater core in it as well. As I stated earlier removing the factory heater would be an alternative to get more room under the dash except you would lose your defrosters.

 

You lose defrost even with the heat/cool unit? I didn't know that. I've never seen a dual unit in person and never really thought about losing defrost. That would certainly be a problem as far as I'm concerned. I'm pretty much out of ideas, except one:

Have you ever thought about installing a factory unit? It's a fair amount of work and involves some cutting of the firewall, but it is very doable. The airflow is excellent. With the underhood work done, the battle is partway won.
I installed factory systems in quite a few of these trucks back in the 80-90's, but there was always a donor available. The inner and outer cases and control heads aren't terribly hard to come by.The dash vents can be made with aftermarket duct and vents.

BTW, what kind of compressor is the new one? York or aftermarket? Just curious.

 

To be quite honest with you, I just assumed that you would lose the defrost function with the aftermarket under-dash unit. I wouldn't think the plumbing would be there for the defrosters. But that does bring up an interesting aspect, I think I will call Nostalgic Air in the morning and ask.

As for the compressor, yes I replaced it with a stock type York. As with hindsight I probably should have replaced it with a more efficient Sanden or some other type, but I was only thinking at the time of ease of installation.

As far as putting the factory air in, it would be way too much work for me to do. I am no longer physically capable of doing that kind of work, but thanks for the suggestion.

 

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