Is it possible to warm up ac?

[david85]

I experimented with this years ago but didn't know enough to get it right and ruined an already weak compressor. Ran too much propane and the old compressor was likely not getting enough oil in the system.

You can get products like Duracool or RedTeck which area premixed blends of propane and isobutane. Having run both over the years, I simply refuse to run R134a. Not efficient, expensive, and not always accessible to the shady tree mechanic.

Congrats on those numbers! You could try the premixed products I mentioned but it looks like you got it nailed as is.

 

[Sidewinded_idi]

I experimented with this years ago but didn't know enough to get it right and ruined an already weak compressor. Ran too much propane and the old compressor was likely not getting enough oil in the system.

You can get products like Duracool or RedTeck which area premixed blends of propane and isobutane. Having run both over the years, I simply refuse to run R134a. Not efficient, expensive, and not always accessible to the shady tree mechanic.

Congrats on those numbers! You could try the premixed products I mentioned but it looks like you got it nailed as is.

Thanks!

 

[jwalterus]

I can't remember if it was mentioned (and I'm too lazy to look at the moment).
But you based your pressures off of R12 for your blend, right?
If your pressures are based off of 134a, you are truly driving a bomb.............

 

[Sidewinded_idi]

I didn't go off pressure. I went off of a lot of research and performance. You can have the pressure as high as you want and it won't make a difference. Our systems have a high pressure burst disk if you got that high but propane at 30psi or 300 is still the same

 

[jwalterus]

I didn't go off pressure. I went off of a lot of research and performance. You can have the pressure as high as you want and it won't make a difference. Our systems have a high pressure burst disk if you got that high but propane at 30psi or 300 is still the same

Basing this off of 2 things:
1) I did these conversions back in the 90s, a lot of us shade-trees learned the hard way with it.
2) Apparently you didn't put in enough research, what's the boiling point of the isobutane at sea level? And at 3 bar? How about your blend?

I'm going to give a quick synopsis of the proper way to do this, and it will explain why you're very wrong, and did this improperly.
It will also show you how to fix this.

Steps:
1) Fix your system, draw vacuum, make sure it will hold a vacuum, add oil and keep system under vacuum.
2) Take an EMPTY 1lb propane canister, draw vacuum in canister.
3) Add isobutane to empty propane canister that is under vacuum.*
4) Top off propane canister with pure propane from 1-lb canister.*
5) Add propane/isobutane mix to system.
6) Add pure propane to top off system, bringing low side pressure to 30-35 PSI while running.

*Mixing the isobutane and propane in this fashion allows them to mix at low pressure. The isobutane has much HIGHER boiling point than the propane, if you add the isobutane to the propane, it will not mix, it will actually remain in it's liquid form in your system since the boiling point of isobutane is over 70°F at 30psi. The boiling point of a 70/30 propane/isobutane blend at 30psi is actually 0°C, which is 32°F.

The fact that your system was putting out such low temps should have been a severe warning if you were to heed it, you thought it was a good thing.
Oh, and any chemistry student in junior high would call that line I put in red either stupid or ignorant. Pressure raises boiling point, why do you think your cooling system is pressurized?

Draw vacuum, remix the right way, set pressures PROPERLY, and see how it performs.+

EDIT: The reason to use pure propane from a 1lb bottle, is the bulk propane in a 20lb is wet and impure. You don't want water in your system do you?

 

[Macrobb]

*Mixing the isobutane and propane in this fashion allows them to mix at low pressure. The isobutane has much HIGHER boiling point than the propane, if you add the isobutane to the propane, it will not mix, it will actually remain in it's liquid form in your system since the boiling point of isobutane is over 70°F at 30psi. The boiling point of a 70/30 propane/isobutane blend at 30psi is actually 0°C, which is 32°F.

Wouldn't it eventually mix, as both liquids end up in the same spot(probably in the dryer, before the orifice)?
It might take a while though...

On the other hand... does it matter? worst case, he ends up with a pure propane system(with very low temps out) and a bunch of 'ballast' isobutane in there taking up space. If it's working, what harm is it going to do?

EDIT: The reason to use pure propane from a 1lb bottle, is the bulk propane in a 20lb is wet and impure. You don't want water in your system do you?

Also, isn't 20lb propane a mixture of propane+butane+isopropane+isobutane+???
Not that it wouldn't work, though the moisture might become a problem eventually...

 

[jwalterus]

Wouldn't it eventually mix, as both liquids end up in the same spot(probably in the dryer, before the orifice)?

Unlikely, the boiling point of pure propane is -44°F (at sea level), so it will remain a gas, that is the reason you introduce the isobutane into a vacuum, it drops the boiling point to below, and as you add the propane, it mixes and drops the boiling point of the mix as the propane is added.

On the other hand... does it matter? worst case, he ends up with a pure propane system(with very low temps out) and a bunch of 'ballast' isobutane in there taking up space. If it's working, what harm is it going to do?

No lubrication, with continual liquid in the system, it's going to have phase separation, his oil and refrigerant are going to separate, and there will be no oil flowing because he'll have oil logging in his evaporator.
Quick compressor death, and with this blend, it could very well be spectacular and burn his truck down.

Also, isn't 20lb propane a mixture of propane+butane+isopropane+isobutane+???
Not that it wouldn't work, though the moisture might become a problem eventually...

Plus ethane , plus high levels of mercaptan which will turn to tar in the system, and the fact that he's in California means that he can only get HD10 (10% propylene, which makes valves stick) at best, and commercial grade propane, which only requires 65% propane content.........

And if there is any moisture in the system, he's below freezing, so.........
ice blockage + pressure = done

I'd either buy redtek (which is just r-209), or buy some RS24

 

[Sidewinded_idi]

I already did all this. It's ignorant to state I did it incorrectly when you don't know how it was done, the isobutane was drawn in under vacuume and the propane used was bernzomatic pure propane not 20lb generic so thanks for the advice but seems like the only negativity I get on this subject is from naysayers and people that personally haven't done it. My truck works fine, low side stays correct and no leaks so I'll enjoy my cold air, not your hot air

 

[jwalterus]

Actually, you never specified how you did it, all you said in your last thread was you re-evacuated the system and refilled it, never said how you made the mix, and you're right, I should have asked that, I was having a bad day yesterday.

I looked back at your other thread, I think I narrowed your issue, I think it's too much flow with the larger orifice.

Answer me this: What are your pressures (and the temp when you took them)? Low, high, and static. Roughly on the high side should be 2Xambient°F+50 (gets you in the ballpark).

The funny thing is, you've gone through all this trouble, when since you replaced both the compressor and accumulator, and flushed the system, you could have just replaced the dryer and gone to 134a and been done with it as well as legal.

Most states have laws on the books against using flammable HCs in an automotive a/c system, I know in ND it's been illegal for years.

Of course, I bought all of the R12 I could find when they did that, I still have plenty of it and the machine to use it......

 

[Knuckledragger]

Going back to the condensation issue for a moment, southern California has been suffering not only high temps, but a monsoon flow of unusually high humidity for a month. As long as his system is not freezing, I would not be concerned about the condensate flow under the vehicle. Maybe prideful.

As for the legality of the mix, I will accept that it could be dangerously flammable if it fails, but laws (especially here) are not always passed only for the protection of the people. Some are written by the industries that are affected and others are created by legislators who have an agenda. In California, we have plenty of both. Seems like he has done plenty of research and is willing to be responsible for the potential damage to his truck, that is good enough for me.

Since I have never gotten past the idea of temperature change by turning a fluid into gas under pressure (or having a working system but balky fan motor), I have been relegated to driving with my windows down, even when it is 110 degrees out. Tip of the hat to all of you cool ones.

 

[Sidewinded_idi]

Actually, you never specified how you did it, all you said in your last thread was you re-evacuated the system and refilled it, never said how you made the mix, and you're right, I should have asked that, I was having a bad day yesterday.

I looked back at your other thread, I think I narrowed your issue, I think it's too much flow with the larger orifice.

Answer me this: What are your pressures (and the temp when you took them)? Low, high, and static. Roughly on the high side should be 2Xambient°F+50 (gets you in the ballpark).

The funny thing is, you've gone through all this trouble, when since you replaced both the compressor and accumulator, and flushed the system, you could have just replaced the dryer and gone to 134a and been done with it as well as legal.

Most states have laws on the books against using flammable HCs in an automotive a/c system, I know in ND it's been illegal for years.

Of course, I bought all of the R12 I could find when they did that, I still have plenty of it and the machine to use it......

I hear what your saying, in ca it's actually legal as long as your not going directly from r12 to it. Basically in short it's only legal to convert an r134 system or an r12 that's already been converted to 134. You may be on to something with the flow statement as the blue orifice tube had the largest inner diameter of all options so that is what I installed under the assumption that the greater effeciency of the refrigerant. Would allow me to move a higher volume of it. Im always open to listening to new ideas and concerns but at this time with the performance and reliability I'm a happy camper

 

[DaveBen]

If it works properly, don't fix it!

 

[OLDBULL8]

I'm surely not a HVAC expert. But if he can't adjust the temp control on the dash and it's set at MAX (he said the Knob is stripped), the compressor is not going to cycle ON/OFF. At the MAX setting there is no temp control. I would say, if the gas (low side) is still not expanding (frost on the line after evaporator or accumulator) the system is not over charged, but with the fan on Hi, he's forcing more HOT air thru the evaporator, but as the Cab temp lowers so does the air temp being forced thru evaporator which will cause the evaporator coil fins to freeze up the more frost on them, the less air thru them.

 

[Macrobb]

I'm surely not a HVAC expert. But if he can't adjust the temp control on the dash and it's set at MAX (he said the Knob is stripped), the compressor is not going to cycle ON/OFF. At the MAX setting there is no temp control.

Pretty sure that our Ford never had any AC temperature control, really... it's either on or off(or, if the low side pressure gets too low, that cuts it off too - I suppose that's some level of non-adjustable temperature control).

The only thing the temp control dial does is activate the blend door - how much air from the AC core vs from the heater core.

 

[OLDBULL8]

Here is what I get searching. I don't drive my 92 much so don't know for sure..

Click on the Blue square to download Pdf.