Making the A/C more effective on an old truck?

[Matthew K]

Hello all,

I've recently acquired a 1983 F100(manual, inline 6). This truck was redone a few years ago with new seating and a new paint job and some other smaller things. It did come with air conditioning from the factory and when it had the makeover a few years ago the a/c was fixed as it had not been working for some time. When it is anything above about 85 degrees(including high humidity), your sweating in this truck even with the a/c on full blast. It's not a huge problem, as I enjoy driving it. But anything to make it more comfortable to drive in the summer would be welcomed.

What I was wanting to know is if there is anything to make the system work better without redesigning the whole system? The engine coolant stays within its normal operating range, so the stock fan seems to be doing its job. Also, it doesn't matter if your idling, or driving 75mph, the a/c output stays the same temp. So I'm led to believe that the a/c system is doing the best it can given its design. I'm curious though, would it be possible to increase the condenser size without upgrading the whole system? Or any other ideas? Like I said, not a huge deal, but I'm just throwing around ideas.

Edit: I'm looking to add some things to this truck, any(reasonable) suggestions would also be appreciated...considering upgrading headlights to LEDs.

 

[bluesideup]

It is likely the refrigerant level present in the system, you may only need to re/charge it? Make sure you do not have a leak before.
To test the air temp put a thermometer in one of the air ducts an see what the temp is? Should be around 40F.

 

[Zeldman]

Anything icing up anywhere?

Have you checked the output from the vent with a thermometer?

Just off the top of my head, look for buildups of leaves and pine needles, possibly an old mouse nest.

 

[Matthew K]

Anything icing up anywhere?

Have you checked the output from the vent with a thermometer?

Just off the top of my head, look for buildups of leaves and pine needles, possibly an old mouse nest.

No blockage that I can see. As far as icing, definitely not on the condenser, but this truck does seem to drip a lot of water(like any other car) as if the air is getting very cold at the evaporator, even though the a/c isn't very cold above 85F.

It is likely the refrigerant level present in the system, you may only need to re/charge it? Make sure you do not have a leak before.
To test the air temp put a thermometer in one of the air ducts an see what the temp is? Should be around 40F.

Well I drove the truck when the a/c system was first fixed up a few years ago, and it was just as bad then, so I wouldn't think it would be low on refrigerant. I do have a gauge to check it with though, so I suppose I should go ahead and check it to rule it out.

 

[Axtel4]

Is it an R-12 system that has been converted to R-134?

 

[Ken]

Insure the recirculation air door is shutting (usually vacuum operated) when in max a/c. Can't cool the cabin if 100 degree air is coming in from outside.

 

[Matthew K]

Insure the recirculation air door is shutting (usually vacuum operated) when in max a/c. Can't cool the cabin if 100 degree air is coming in from outside.

How would I go about doing that?

 

[Matthew K]

Is it an R-12 system that has been converted to R-134?

I just checked the new ac compressor that has been on it, and according to the manufacturer it was made for r-12 systems and was manufactured in 2011.

 

[azblackbird]

How would I go about doing that?

Usually under your dash above the floor of the vehicle. Look for a vacuum actuator(s) with some linkage attached to it. Switch between your A/C and heater and listen for, or do a visual on wether or not it's opening or closing your vent doors. I had to replace one on my Chevy P/U a couple years ago as my A/C was blowing hot air because it was mixing with the air from the heater core. Not long after that, the blower speed modulator board took a dump, so I had to replace that also. Watched a couple YouTube videos for both procedures. Both were easy jobs and ordered the parts I needed off Amazon.

 

[Skip Miller]

1) Are you sure that r12 was installed, or is it using R134 by mistake? I'm just spitballing here - I don't know for sure if running the wrong refrigerant will cause your symptoms... -Skip

 

[Criitter7]

Before going any further I'd need to know what high side and low side pressures are. Without it you can't properly diagnosis the problem

 

[PaulS]

The older systems had a sight glass on the drier/filter, many of them any way. Check it if you have one, there should be no bubbles. If there are you need more Freon. Beyond that, make sure the condenser, (the one on the out side of the car) is clean. Blow it out with compressed air and clean it as best you can. Then as others have suggested, make sure the doors inside are actuating.

 

[AKBill]

Before going any further I'd need to know what high side and low side pressures are. Without it you can't properly diagnosis the problem

This is very true, you need to see how the system is cycling to diagnose the problem

 

[Matthew K]

Before going any further I'd need to know what high side and low side pressures are. Without it you can't properly diagnosis the problem

This is very true, you need to see how the system is cycling to diagnose the problem

Well considering it appears to still be a r-12 system, is there a way to check it without buying an expensive gauge setup?

 

[Criitter7]

Well considering it appears to still be a r-12 system, is there a way to check it without buying an expensive gauge setup?

I would just convert to 134, no point and hanging on the r12 stuff. Any parts store will have a conversion kit. Then just some cheap 134 gauges would work. Now finding Someone to evacuate the r12 is the hard part. Unless you just dump it in the air yourself.

 

[Criitter7]

Also while apart get an evaporator cleaning kit and clean it out. Oil and gunk stick to the walls and it doesn't exchange the cool(what ever the word is im having a dumb ass attack right now) to the evaporator.

 

[Matthew K]

Insure the recirculation air door is shutting (usually vacuum operated) when in max a/c. Can't cool the cabin if 100 degree air is coming in from outside.

Excuse my ignorance, but would this vacuum powered motor be what controls the re-circulation door?

 

[Zeldman]

Excuse my ignorance, but would this vacuum powered motor be what controls the re-circulation door?
View attachment 54550

That appears to be the one you are looking for. It has been too long of a time since I worked on vehicles for a living. Can you move it by hand?

And don't consider converting a R-12 to 134. It just doesn't work for older vehicles.

 

[Matthew K]

That appears to be the one you are looking for. It has been too long of a time since I worked on vehicles for a living. Can you move it by hand?

And don't consider converting a R-12 to 134. It just doesn't work for older vehicles.

I can move it, sounded like I was crunching something a little bit when I did it though. With engine running, I went through all the a/c and heat options and the motor didn't move at all.

 

[Zeldman]

Try moving by hand and see if the temperature of the air coming out the vents feels cooler or hotter.

With the age of the truck there is a slight possibility that there is a mouse nest inside stopping or slowing air movement.

 

[Matthew K]

Try moving by hand and see if the temperature of the air coming out the vents feels cooler or hotter.

With the age of the truck there is a slight possibility that there is a mouse nest inside stopping or slowing air movement.

As far as testing temp change, already did that, didn't notice any change for the short time I tried it. Should probably go ahead and check for debris blocking it though.

 

[Axtel4]

Converted a mid eighties Ranger from R-12 to R-134 in the mid nineties. It worked very well but required some prep work. I had to suck down the system, replace the accumulator and the orfice tube (R-134 requires a different tube) pulled a vacuum to boil out the moisture and recharged the system. The cooling was within a couple of degrees as the R-12. Ran that way for almost 20 years until my son totalled the truck at 235k miles.

 

[bdtaz]

Here in AZ, I have been forced to learn more about auto AC then I really want to.

If it was converted to R 134, your system fittings should now be "quick disconnect" fittings with a different fitting for the high side versus the low. If the fittings are screw on and both the same size, there is a good chance it is still R-12

If it is R 12 and it still has Freon in it, keep it R-12. You can generally find R-12 on Craigslist for about $20 a can and R-12 gauges/hoses at yard sales.

I have converted a couple R-12 vehicles to "Enviro Safe" working fluid. I expect it is butane based or equivalent but it seems to have been working fine the past five years without leaks or issues in two systems with many components over thirty years old. A good bit cheaper then R-12 but more expensive then R-134 at WallyWorld. While it is flammable, I expect it is probably less risky then the already present gasoline as it will dissipate pretty quickly if the the system is breached.

And as pointed out above, go through the various dampers/doors and the vacuum line/motors that operate them.

 

[Clark1961]

Here in AZ, I have been forced to learn more about auto AC then I really want to.

If it was converted to R 134, your system fittings should now be "quick disconnect" fittings with a different fitting for the high side versus the low. If the fittings are screw on and both the same size, there is a good chance it is still R-12

If it is R 12 and it still has Freon in it, keep it R-12. You can generally find R-12 on Craigslist for about $20 a can and R-12 gauges/hoses at yard sales.

I have converted a couple R-12 vehicles to "Enviro Safe" working fluid. I expect it is butane based or equivalent but it seems to have been working fine the past five years without leaks or issues in two systems with many components over thirty years old. A good bit cheaper then R-12 but more expensive then R-134 at WallyWorld. While it is flammable, I expect it is probably less risky then the already present gasoline as it will dissipate pretty quickly if the the system is breached.

And as pointed out above, go through the various dampers/doors and the vacuum line/motors that operate them.

Propane is more likely than butane. Butane boiling point is too high. As for the risks - if the system is breached move many yards away until everything dissipates. There will only be a couple pounds present but there's a fair bit of energy there and the flame front moves along crisply. Propane is what's used in fuel-air explosives.

On the other hand propane is a good working fluid for refrigeration systems...

 

[TommyG]

Is R 12 still available anywhere. I remember about 15 years ago R 12 was very high price due to the lack of availability.

 

[bdtaz]

I have been able to purchase it via private party sale(like Craigslist) for around $20/can whenever I've needed it and one of my friends recently purchased some via E Bay for around $30/can. There seems to be a good bit of "New, Old Stock" around as people squirreled it away by the case when it was phased out in the 90's.

There is an online test offered to give you a EPA certification (https://www.epatest.com/609/openbook/) that would allow you to purchase it retail.

So while not cheap, In my opinion, if you have a R-12 system that still has most of a charge in it without any obvious leaks or other problems, it is still more cost effective to simply top it off with R-12.

If the system is completely empty, you are probably better off properly converting to R-134 or making your own risk/reward decision on the flammable alternatives. Note if you go to one of the alternatives, it is unlikely any shop will touch the system from that point on.

 

[AKBill]

Well considering it appears to still be a r-12 system, is there a way to check it without buying an expensive gauge setup?

The gauge sets are not that expensive, but without knowing what you are looking at it would most likely be better to take the truck to someone who deals with R12 A/C systems. They can determine if the system is just low if it has leaked down to zero charge they can find the leak. If it is just low they can top it off and do a complete system check.

Converted a mid eighties Ranger from R-12 to R-134 in the mid nineties. It worked very well but required some prep work. I had to suck down the system, replace the accumulator and the orfice tube (R-134 requires a different tube) pulled a vacuum to boil out the moisture and recharged the system. The cooling was within a couple of degrees as the R-12. Ran that way for almost 20 years until my son totalled the truck at 235k miles.

This is pretty much what it takes to convert R12 to R134a, I may add it is also good to flush the system after evacuating it. The oil used in the R12 system is different than that used in the R134a system and needs to be added before charging the system

I have been able to purchase it via private party sale(like Craigslist) for around $20/can whenever I've needed it and one of my friends recently purchased some via E Bay for around $30/can. There seems to be a good bit of "New, Old Stock" around as people squirreled it away by the case when it was phased out in the 90's.

There is an online test offered to give you a EPA certification (https://www.epatest.com/609/openbook/) that would allow you to purchase it retail.

So while not cheap, In my opinion, if you have a R-12 system that still has most of a charge in it without any obvious leaks or other problems, it is still more cost effective to simply top it off with R-12.

If the system is completely empty, you are probably better off properly converting to R-134 or making your own risk/reward decision on the flammable alternatives. Note if you go to one of the alternatives, it is unlikely any shop will touch the system from that point on.

I agree if the system has zero charge I would convert it to R134a IMHO. Good luck with staying cool... Living in SE Alaska I only need to worry about running my a see a couple of times a year. Have not used it in 2017 yet...

 

[GlennAB1]

Just a few thoughts. Door seals allowing heater core air to leak. Vehicle insulation, adding a thermal barrier between the top clip "roof" and headliner, and between the floorboard and carpet can help a lot.

 

[Matthew K]

Just a few thoughts. Door seals allowing heater core air to leak. Vehicle insulation, adding a thermal barrier between the top clip "roof" and headliner, and between the floorboard and carpet can help a lot.

I can definitely imagine that adding insulation would help. As you may or may not know, these F100s have no insulation on the roof and the windows probably let a ton of heat in also.