R-12 Refrigerant swap?

[arco777]

So my 94 Explorer has a good working R-134a equipped system with a clean bill of health. But it's not as cold as I'd like. Feels just like I'd expect a system designed for R-12 but factory retrofitted to R-134a use would be - underpowered.

Heard talk of how the R-12 systems performed much better and from what I've read, R-12 cools better. Called my local AC shop and they confirmed they are able to put R-12 into my system if I provide the R-12. I can get R-12, it's just not cheap. But would be worth it to me in this 100 degree heat.

Any input, anyone, on this (backwards) swap? As far as I know, I wouldn't have to change any seals, and compressor oil probably won't be an issue. Anyone experienced Explorers with both types of refrigerant and noticed a large difference?

 

[BrooklynBay]

I'm surprised that you could find R-12. I wouldn't want to risk doing damage to the system just in case it's not compatible. Did you try a variable orifice tube? They are supposed to be more efficient. Check to see if your heater control valve is working properly. Do you have a single or dual A/C system?

 

[BrooklynBay]

I forgot to mention earlier that the low pressure cut off switch is calibrated a little different for each type of freon. It's not a major difference since the old switch works when you swap R-134A into an R-12 system. Another issue is with the adapters. You will have to find an adapter to transfer R-12 into the new style R-134A adapter. It might be hard to find.

 

[arco777]

I'm surprised that you could find R-12. I wouldn't want to risk doing damage to the system just in case it's not compatible. Did you try a variable orifice tube? They are supposed to be more efficient. Check to see if your heater control valve is working properly. Do you have a single or dual A/C system?

Finding R-12: It's Arkansas, the weirdest stuff comes out of the woods and goes up for sale when people need money. Buying it should be no problem.

Compatibility: I would think that everything should be compatible; if R-12 particles are larger than R-134, the seals I have should be happy and so should the compressor I'd think. Somehow I doubt that Ford bothered to change anything but the seals in the design when they changed refrigerants.

Orifice Tube: Did not know about the variable tube. Looked it up and I can get one like that cheap, and I was going to change mine at time of service anyways. I assume the one listed for "Severe Duty 105*+ climates" is what I'd want? Are these things reliable?

Heater Valve: Working properly.

Single/Dual: I assume you mean do I have rear air? No, just front.

 

[arco777]

I forgot to mention earlier that the low pressure cut off switch is calibrated a little different for each type of freon. It's not a major difference since the old switch works when you swap R-134A into an R-12 system. Another issue is with the adapters. You will have to find an adapter to transfer R-12 into the new style R-134A adapter. It might be hard to find.

Cutoff Switch: So my existing switch should work ok? I can change if necessary, it's just that I want to keep R-134 seals as much as possible and save money. I do plan to change out the dryer at time of service as well, but with a R-134 unit.

Adapters: My local AC shop confirmed that they have an old R-12 AC rig, and the necessary adapters to hook up to my R-134 connections. Got a "lolwut" from the service tech at first, said in 20 years he hadn't heard anyone wanting to swap backwards to R-12 like this.

 

[obie]

Do you have the EPA HVAC cert? I can't remember whether its 608 or 609, but you need to have one or both to be able to buy R12 legally.

 

[Jason94sport]

The r12 pressure switch will not fit. The threads are bigger on the 134A one.
What is your vent temp now? What are your pressures? An evac, & cleaning of the lines & condenser & recharge may help things.

 

[Roadrunner777]

I'm going to ask a question Brooklyn asked earlier. There is a heater bypass valve that bypasses the heater core when the AC is on Max. It also does something with an internal/external air flap. The AC will feel weak if this stuff isn't working. This is all driven by vacuum in those little black plastic lines. Have you looked at this at all? You could have a leaking line and a $2 fix.

 

[Maniak]

Orifice Tube: Did not know about the variable tube. Looked it up and I can get one like that cheap, and I was going to change mine at time of service anyways. I assume the one listed for "Severe Duty 105*+ climates" is what I'd want? Are these things reliable?

Heater Valve: Working properly.

On Every Ford A/C system I work on I put in the Variable orifice tube. It does increase the high side pressure at idle but it really helps cooling.

Before the Black death got the best of the system on our '92 we could get Sub 40F air at idle with the fan on 3. It was only in the 90's then (doors open).

Even with the black death and compressor issues I'm getting 50F (high idle) air when its 105f outside with the fan on 3.

Some keys to good cooling are the pressure differential and ability to remove the heat from the condensor.

~Mark

 

[arco777]

I'm going to ask a question Brooklyn asked earlier. There is a heater bypass valve that bypasses the heater core when the AC is on Max. It also does something with an internal/external air flap. The AC will feel weak if this stuff isn't working. This is all driven by vacuum in those little black plastic lines. Have you looked at this at all? You could have a leaking line and a $2 fix.

Verified heater valve is working properly and air recirculation is working.

 

[arco777]

The r12 pressure switch will not fit. The threads are bigger on the 134A one.
What is your vent temp now? What are your pressures? An evac, & cleaning of the lines & condenser & recharge may help things.

Vent temp is hard to say as I don't have a thermometer. As for pressures, I had the whole system tested last summer when I wasn't happy with the system's output. The system was reading fine but I had them evacuate the system, pressure test it for leaks, filled with dye and new refrigerant and oil. The shop gave my system a clean bill of health. They did not take the system apart to check the orifice tube or for debris. I cleaned the condensor as best I could.

 

[arco777]

On Every Ford A/C system I work on I put in the Variable orifice tube. It does increase the high side pressure at idle but it really helps cooling.

Before the Black death got the best of the system on our '92 we could get Sub 40F air at idle with the fan on 3. It was only in the 90's then (doors open).

Even with the black death and compressor issues I'm getting 50F (high idle) air when its 105f outside with the fan on 3.

Some keys to good cooling are the pressure differential and ability to remove the heat from the condensor.

~Mark

Currently it is averaging 100* outside daily, and humidity varies. The air I'm getting out of the vents at best is maybe 60*-ish, I'd estimate. I have tinted windows and no sunroof, use a shade while parking and crack the windows too. It takes quite a while to get anywhere near comfortable, at least 20 miles of driving.

 

[arco777]

Do you have the EPA HVAC cert? I can't remember whether its 608 or 609, but you need to have one or both to be able to buy R12 legally.

Ummm.... sure... somewhere

 

[Maniak]

Currently it is averaging 100* outside daily, and humidity varies. The air I'm getting out of the vents at best is maybe 60*-ish, I'd estimate. I have tinted windows and no sunroof, use a shade while parking and crack the windows too. It takes quite a while to get anywhere near comfortable, at least 20 miles of driving.

I don't think your going to be able to get much better without spending some money to figure out where the problem is.

Grab a candy thermomether to throw in the vents to figure out the rear output temp and pick up a manifold set so you can check your own pressures..

HarborFreight has the manifold set for $53 right now and the candy thermometer is < $5-ish at the supermarket.

You can also save money by evactuating the system yourself too.. Its < $110 for a a/c vacuum pump from HFT right now too..

If you can't find the coupons for those let me know.

It only takes 2 times of working on your own a/c to make up the cost of the tools.

I almost forgot.. A weak fan clutch can also cause issues.. You really need good air flow through the condensor to get rid of the heat load.

~Mark

 

[arco777]

I don't think your going to be able to get much better without spending some money to figure out where the problem is.

Grab a candy thermomether to throw in the vents to figure out the rear output temp and pick up a manifold set so you can check your own pressures..

HarborFreight has the manifold set for $53 right now and the candy thermometer is < $5-ish at the supermarket.

You can also save money by evactuating the system yourself too.. Its < $110 for a a/c vacuum pump from HFT right now too..

If you can't find the coupons for those let me know.

It only takes 2 times of working on your own a/c to make up the cost of the tools.

I almost forgot.. A weak fan clutch can also cause issues.. You really need good air flow through the condensor to get rid of the heat load.

~Mark

Thanks! Food for thought.

 

[BrooklynBay]

Make sure that the front condenser is clean. Sometimes bugs & road dirt could get between the fins. How many degrees is the thermostat? What's your average engine temperature?

 

[arco777]

Make sure that the front condenser is clean. Sometimes bugs & road dirt could get between the fins. How many degrees is the thermostat? What's your average engine temperature?

Condenser has been cleaned. Thermostat is OEM replacement; recently put a new stat, hoses, and radiator on just as preventative maintenance. Average temp stays around the O in NORMAL and doesn't really ever get noticeably higher.

 

[4x4junkie]

I did a R-12 to R-134a conversion on my BII. I was getting 38° air out of the 2nd-from-right vent on a 95° day while on the road. Much colder than that and I suspect ice might start clogging up the evaporator.
My Ranger came factory with R-134a and it too blows in the very low-40°s with a full charge of freon in it... Which tells me for sure you got something wrong on yours if it's only blowing 60°. Back-converting to R-12 isn't the answer.


Some good suggestions have already been given... I would add to them: Swap to a heavy-duty fan clutch, and also make sure the gap between your condenser and the radiator is sealed (this so that air drawn in by the fan doesn't bypass around the condenser).

 

[Jason94sport]

My bet is your orifice tube is gunked up.

 

[surf]

I agree that there is something wrong. The performance of the retrofitted system should be better. My '93 was converted and it blows cold enough that I end up turning it down after about 20 minutes.