Udating A/C in 79 PC

[hcmclean]

What parts do I need to update the A/C from r12 to r135?

[PaceFever79]

Hi, you do know you can still get r12 on eBay?

It's a bit pricey, but a lot less than a full conversion to r135.

[grabbergreen84]

You could also run that system on propane...



You definitely need to get all traces of mineral oil out of the system, as the R134 uses pag oil.
Beyond that, you might benefit from changing out some of the hardware, like maybe the old flathead compressor for a newer style one. You'll need to change the accumulator/dryer for sure.

I've often wondered how much of the AC system from a '94 and later Mustang could be swapped into a Fox. That would 've been an R134 system from the get-go.

[wraithracing]

I don't recommend the conversion to R134 the system was never designed for it and honestly the conversion doesn't work that well either. Besides the cost of R12 has come down quite a bit in recent years due to lack of demand. In many cases the R12 is only around $30-50 or so a pound. I would recommend having a local licensed A/C shop recharge with R12 and you will be much happier with the results. The overall cost will not be that much more than the R134 conversion and again it will work much better, especially in the heat and humidity of Texas.

[wraithracing]

I've often wondered how much of the AC system from a '94 and later Mustang could be swapped into a Fox. That would 've been an R134 system from the get-go.

The A/C condenser unfortunately doesn't fit properly without modifications. Ask me how I know. The rest of the system could be made to work, but the SN95 system moved the Compressor to the location the air pump is on the 79-93 cars, so it will take some fabrication and tweaking.

Trey

[84GT350CONV]

My car was converted to R134 before I got it and it cools the car fine in the middle of the hot Texas summers. Maybe not quite as efficient as R12 but it gets the job done. I was told it got a new receiver/dryer and new O ring seals after the system was flushed.

[grabbergreen84]

O ring seals

Oh yeah. I forgot those.
The next most important part after getting all of the mineral oil out and changing the accumulator/dryer...

[82GTforME]

Old thread resurrection instead of starting a new one!

As I take our 79 Ghia engine trim all off and apart as part of the resto and getting to the AC compressor and related parts it got me thinking what I want to do. I do not know if the AC worked or not when we first bought it. It still had a little refrigerant in the system when I disconnected them a couple of years ago.

As the plan is to keep the car as original looking as possible and functioning if I can, I have a list of parts I need. As I was online looking for other parts on the usual online sites I see that Rock Auto has new and reman compressors for a 79. They state they are at least and they look correct. With R12 basically illegal up here in Canada I saw that Rock Auto carries compressors ready for R134a:

https://www.rockauto.com/en/moreinfo...t=6628&jsn=126

You definitely need to get all traces of mineral oil out of the system, as the R134 uses pag oil.
Beyond that, you might benefit from changing out some of the hardware, like maybe the old flathead compressor for a newer style one. You'll need to change the accumulator/dryer for sure.

While a boat anchor, I'd like to maintain the flathead compressor and may consider the above or similar option. With the entire system apart and only the evaporator in the dash, how would I go about removing the previous mineral oil residue or other debris or contaminants out? Any options for the dryer out there readily available that is a direct swap for R134a. PS: I may still take the dash out to get the heater core changed, I may be better able to access it later.

I don't recommend the conversion to R134 the system was never designed for it and honestly the conversion doesn't work that well either.

Hi Trey, As I mentioned I'd like to maintain the originality. I see three options in no particular order:

1. Remove the system completely including brackets to be a "non-AC" looking car. I don't live in a super hot area but AC would be nice for the odd hot enough summer day the car may actually be on the road.
2. Upgrade the system now to R134a while I have everything apart and maybe the best opportunity. I would need to confirm what exact parts I would need: compressor, o-rings, dryer?
3. Reinstall all parts I have after cleaning up and refurbishing, disable the AC (not hook up the wire) and let the pulley spin.

[85GTGuy]

Here's a kit for an 82-85 R134a conversion. While I know it's not for a 79, it may at least give you an idea of what all is required

https://lmr.com/item/LRS-19703A-K/mu...rsion-8385-50l

[wraithracing]

Being that you are in Canada I would assume that although he deal with heat in the summer it's not quite south Texas heat and therefore it won't put the same strain on the system trying to cool in the south would be. With that caveat, you can probably get a reasonable working R134a system that looks essentially stock.

In my experience the condenser at the front of the vehicle is one of the biggest deciding factors in how effectively a retrofit system will cool. The newer core designs are much more efficient than the old fin and tube style that are standard replacements.

I have not researched doing what you are trying to do. I just swapped out the HVAC parts and pieces from an 83-86 model Mustang into my Pace Car and called it good. Cut the proper hole in the firewall and was done. Looks factory and only the hard core Fox people know that it's not "correct".

R134a moleculars are smaller than R12 and therefore are able to leak from R12 designed hoses. So all of your hoses have to be designed for R134a refrigerant. Most are these days, but if you are buying standard replacements can't guarantee that.

Most compressors will list as R134a these days, but generally all that means is that they come empty with no oil and therefore you add the appropriate oil for your vehicle manufacturer and R134a and there's no issue due to the wrong refrigerant oil.

Flushing out the system can be done with any of the standard flushing fluids. If you are replacing the majority of the parts, then flushing is less of a concern other than maybe the evaporator core in dash.

I would personally recommend looking at the aftermarket A/C companies like Vintage Air, Classic Auto Air, Old Air Products, Restomod Air, etc. for the condensor and the receiver/dry. The odds are the aftermarket has a newer design condenser that is much more efficient than any stock replacement and with some minor modifications will fit the Mustang and look stock. Same for the receiver dryer assembly. This will most likely require custom hoses to connect everything, but you can get cut to fit from most of the manufacturers and then have a local shop install the fittings once you determine the overall length and routing. Just pay attention to fitting orientation when marking any lines.

This might be a little bit more work to begin with, but in the long run you will most likely have a much better performing A/C system than if you just swap out original parts for replacement parts and fill it full of R134a. I know in my experience when Hoze Wizards was around and offering the kits to convert the Fox Mustangs to R134a that just their newer model condenser ( which was nothing more than an OEM condenser from a newer model Ford that fit) alone dropped my interior temps 10 degrees cooler while still using the original FS6 compressor and not the Sanden that came in their kit. Living in Texas at the time that made the A/C actually worth spending the money on as it actually cooled the car in the middle of the summer. Best of Luck!

[Chuck W]

I did an R134a conversion on the LTS when I put it back on the road. I don't know all the particulars of the difference in the systems (85 vs 79), but I'm all for a conversion to R134a from R12.

I think the biggest change is the condenser. The old tube and fin type just really doesn't cut it. Unless you're being a stickler for originality over function, the ones produced these days are of the piccolo or parallel flow types, which are much more efficient.

You didn't really give folks much info about your car. Is it the V8 or I4 turbo? Factory air?

I don't think the pump type would be a problem, but finding replacement hoses might be.

On the LTS, I flushed the old compressor and refilled with the proper oil. Used a newer condenser and pressure-checked the evaporator. All the hoses needed to be replaced anyway (Were all cut by a previous owner) as did the drier.

The car gets COLD with the R134a.

[wraithracing]

The 79 cars use an H valve instead of the expansion tube inline. That seems to be one of the biggest issues with conversions is getting that to function properly due to the difference in pressures. The 79 also uses a receiver/dryer instead of the accumulator. Not a huge difference, but again affects the overall function of the system. Obviously most of the aftermarket systems use a receiver/dryer since they are smaller and easier to retrofit to a vehicle that didn't originally have A/C. So they can be made to work well, but as we have mentioned I feel using parts that were developed for use with R134a is the best option to get the best performance. Otherwise they system never really works well. Yes, it cools, but seldom will it actually get cold and to the point where the system doesn't have to operate a maximum all the time.

[82GTforME]

Hi Chuck, to clarify this is a 79 Mustang with 302 V8. Factory AC.

http://vb.foureyedpride.com/showthre...um-Blue-Bomber

After reading through the first response from Trey a few times and doing some quick researching on the sites he recommended I am on the fence. Cost and effort versus actual need. Our other 79 with black interior and no AC isn't insufferable on the odd hot day I am out in the car. Same for my 86 SVO. It isn't really a huge concern now (maybe global warming will necessitate it in the coming decades although gasoline may be banned by then! ).

VintageAir looks to be the only one that had a Fox set up or parts. No individual parts available that I could see. The condenser kit looks good but appears to move the hose connections closer to the middle from the top. That may have the original hoses not fit and add further cost and possibly aggravation

I found this article on the Hagerty site. Maybe a bit far fetching after reading the new replies above.

https://www.hagerty.com/media/mainte...s-and-the-law/

Over time, a credible middle ground emerged. As long as the compressor was working well, it could be drained, filled with R134a-compatible oil, and reused. An R134a-specific expansion valve was preferred but not strictly necessary. The concern that the original R12 hoses would leak R134a like a screen door on a submarine appeared to be largely unfounded, as the insides of original hoses seemed to naturally become impregnated with a combination of refrigerant and oil that acted as a barrier. So as long as the system was functioning correctly and not leaking, it appeared that you could flush the system of any old oil, change the oil in the compressor to PAG or ester oil, replace only the receiver-drier and the o-rings, screw on the charging port adapters, evacuate the system, and recharge it with the new R134a, using about 80% as much as the original R12 volume.

I am honestly looking for the least painful and least costly way to do this restoration. If I could get an AC system converted and working with the stock parts I have by flushing the system and compressor, changing the o-rings and changing the oil. The loss of efficiency where I am may not matter.

What concerns are there if I cannot get a simple solution to change the receiver/dryer and use the original one?

Here is the stock set up which I have already cleaned up and refurbished:



It would my intent that after I complete the car and get it running I would have the professionals purge and fill the system to try it with R134a.

Worst case ending I suppose:

3. Reinstall all parts I have after cleaning up and refurbishing, disable the AC (not hook up the wire) and let the pulley spin.