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1991 F-150 AC Upgrade

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  #1  
Old 05-01-2017, 02:46 PM
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1991 F-150 AC Upgrade

Hello all again!

Fixed Fuel tank issue, next project is my air conditioning.

Ordered a chilton repair manual to help me along.

I want to do a full overhaul of the AC. So far, what I know is that when I switch it to AC, it blows, but nothing cold or hot comes out of the vents. Doesn't matter what temperature I put it on. I don't need heat as I live in Florida, but AC would be nice, soon, as it is getting hot.

I assume I am going to have to convert the R-12 to an R-134a system, how do I do that? Instead of trouble shooting every part, I am just buying a new:

Condensor
Evaporator
Accumulator

The actual compressor looks like it was replaced once so I am going to see if it works before replacing.

Where do I go from here, after replacing those parts? I assume I have to charge the AC system somehow, is there any other parts I need? I attached a picture of my current system installed.
Is there a kit I can purchase perhaps?

I don't know what those two tubes are that are cut... should I replace those or hook them up to something?


 
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Old 05-02-2017, 12:43 PM
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The 2 cut hoses are for the heater core, odds are it probably leaked down the interior so someone cut the hoses going to it to bypass it. You can replace the hoses and the core if you wish to have heat.

The blower motor is in the dash, all that stuff is the ducting for the a/c and heat as well as max a/c function

To do a full 134 conversion you'll need all the hoses, a new condensor, maybe the compressor if yours doesn't spin on or the clutch doesn't kick in, probably a new evaporator, a new orifice tube and a new accumulator/dryer assembly. As well as access to a set of manifold gauges and a vacuum pump or a recovery/charging machine and obviously the 134 refrigerant.

I did a complete overhaul on my truck right after I got it, all that stuff was like $350 from rock auto. I already had a set of manifold gauges and rented a vac pump to vac the system down to make sure it didn't leak after all that work. 2+ years later it's still icy cold here in AZ.
 
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Old 05-02-2017, 01:06 PM
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The blower motor is not in the dash, you can see it in his pic, the round thing lower left.

I can see your vac hoses for the HVAC system are shot, that is why it always blows out the bottom (or maybe it's the defrost, can't remember) no matter what you set the system to.
 
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Old 05-02-2017, 04:56 PM
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Go on ebay and get the kit and it will be a UAC kit with everything you need except maybe the liquid line hose. However, I have been thru 4 condenser that I bought and none of them are actually exact fits and none of them are like factory. None of them have robber grommets or bushings so I went down to autoparts store and got what I needed to flush the evaporator core and the condenser myself. It worked perfectly as long as you also have compressed air. No aftermarket condenser out there is as good as your factory condenser and none of them fit properly so do not be lied too.
 
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Old 05-02-2017, 05:35 PM
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Looks like someone already converted it. The fitting on the receiver dryer is r134. You could partial charge and see where the leaks are, but from the looks from the rust you're going to want to replace everything. Most of the parts are the same r12-r134 with the exception of the receiver dryer and the manifold line. Cross parts between yours and a 94-96 and you'll see what is the same. You should be able to reuse your evaporator and condenser assuming they don't leak. I just converted over my 93 explorer.
 
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Old 05-02-2017, 06:58 PM
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Originally Posted by jas88
The blower motor is not in the dash, you can see it in his pic, the round thing lower left.

I can see your vac hoses for the HVAC system are shot, that is why it always blows out the bottom (or maybe it's the defrost, can't remember) no matter what you set the system to.
I second theses thoughts. I think you are putting the cart before the horse. Are you getting power to the compressor? If you jump the low pressure switch does the compressor kick on? You need to put some gauges on it and see what pressure readings. Your first course of action is to get those vacuum lines repaired.

As far as the heater core is concerned, there is an access panel behind the glove box. I have replaced the heater core in my truck(s) in about 15 minutes so I'm not sure why they would have bypassed it. It does still cool off in Florida.
 
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