standarche

I promise I've done my due diligence searching for help on this, but I'm not as smart as everyone else when it comes to cars so I'm still a little lost.
About 2 months ago my a/c stopped blowing cold air, before that it was very cold and only worked on high(just replaced the blower resistor today to solve that problem). From reading other threads I've decided to start with the low pressure switch, but I don't know where it is. I saw a picture with it saying its to the left of the rpm nob on the a/c computer thingy, but i don't know what it looks like. I'm willing to research it myself if someone can post a link, or just tell me what it looks like. I have a 91 pickup v6 if that matters at all, thanks.

standarche

I just went out and looked in my peeker glass window to check the r12 fluid level, and I couldn't see anything. Does the fact that the compressor doesnt kick in effect that, or could that be the reason it doesnt kick in?

YodaPala

If the system is flat or has little refrigerant the compressor will not kick in. Get a guage set and hook on to the system and see what you got in there first. Your not going to see anything in the sight glass unless the compressor is running. The sight glass is used for charging the system, add refrigerant until all bubbles are gone, then system is fully charged correctly.

You might consider retrofitting to 134a because R-12 is ungodly expensive.

Good luck

Matts90Runner

R12 cools better/more efficient.

tim a.

r 12 is about $20 a can,but you can get it cheaper if you wait and bid on ebay.Mine was about $30 shipped for 2 cans. you need 2 14 oz cans,not 12.I wont convert anything to 134 until I cant buy r12 anymore.

The MAN

a converted R134a system might not work as good as it was with R12, but I've done conversions on both my old 'yotas and they cool plenty fine... they work good even in this 100+ texas heat! I admit they don't blow quite as cold as it was with R12, but the difference is very small... too small to even care in fact

as long as you do the conversion properly, and the radiator fan is in good working order, it will work fine

the sight glass is useless once you go to 134a btw

cody o

I'll add my input since I've recently fixed three R12 systems, learning everything from scratch.

They were all non-functioning due to low refrigerant pressure. One system had already been converted from R12 to R134a by the previous owner. I bought a set of R12 gauges off eBay ($40), a venturi-style vacuum pump from Harbor Freight ($15), and a case of hydrocarbon HC12a refrigerant from OZ Technologies (twelve 6oz cans for $65, each 6oz can is equivalent to 17oz of R12). I also bought a R134a conversion kit from Advance Auto ($11) because I read somewhere the conversion adapters had to be added to make it legal. Whatever.

Yes, I've read all the fear-mongering about using hydrocarbon refrigerants in vehicles, but I have seen absolutely zero evidence there is any explosion hazard. None. Period. (I looked, I promise!)

Results:
The conversion was absolutely amazing in two of the vehicles (91 4runner and 87 van). It will freeze your nuts off!!! I took a trip in the 91 4runner and we had to keep the heat turned up because it blew so cold, even though it was 100 plus degrees outside. The third vehicle, 86 cressida, had a badly damaged compressor from the previous conversion to R134a. R134a has significantly higher pressures than R12 and will damage the older systems for various reasons.

It's an option. I've been very pleased with the results, but it may not be for everyone.

PS- If anyone's interested I could do a write up on the conversion.

The MAN

well if you found zero evidence, why do you think the EPA has banned all flammable refrigerants for automotive use?

You read somewhere that conversion adapters had to be added to make it legal, but you didn't read enough of the fact that each different refrigerant is supposed to have unique fittings... so in otherwords, even if your HC12a refrigerant was legal, what you've done is still illegal as you're using R134a fittings... let's just hope none of those vehicles goes to a shop and gets cross contaminated with their 134a machines! That is the sole reason why fittings must be unique

the compressor got damaged because of lack of oiling... pressures have nothing to do with it... R134a pressure gradients are very similar to R12, only just slightly higher... they are close enough that you can still use low side pressures to determine what the temperatures are at the registers

those "conversion kits" sold at auto parts stores are a sin to the automotive world... people buy them expecting they can just screw the adapters on, and just shoot a couple of cans of the 134a in and expect cold air... what most people don't know is R134a requires a completely different kind of oil... the original mineral oil WILL NOT WORK, it will just settle into the low parts of the system and do nothing... the compressor burns up as a result... the desiccants in R12 systems are also different, which is another thing people don't know and must also be changed out when doing a conversion... the driers hold most of the oil and by replacing it, you also get rid of the mineral oil and replace it with PAG or ester oil

improper repairs is the a big cause of A/C failures, plain and simple
blaming conversions as a cause of failures is baseless and ignorant because if that was such a case, no auto maker would approve conversions in the first place

cody o

The MAN, I agree with you completely about the "conversion kits". I think what you described is exactly what happened to this particular car. The two oils do not mix, and will destroy the equipment if you don't properly evacuate the system first.

That said, you were awful quick to label me as ignorant. I didn't want to get into a debate about the EPA/legality stuff as there are countless threads and endless debates on the topic already littering the interwebs. From my research, the EPA does not allow conversion of R12 systems to hydrocarbon, but does allow R134a to hydrocarbon. So... "convert" the R12 system to R134a, then to hydrocarbon. Each refrigerant does not require its own unique fitting. Just look at your R12 gauges; they will fit R12, R22, and R502 systems. Any mechanic working should, as a matter of course, check the refrigerant label that clearly labels the system as containing hydrocarbons.

I have seen absolutely zero evidence that hydrocarbon refrigerants pose any safety threat. If I had, I wouldn't have put it in the vehicles that by brother, sister, and fiance drive every day. If anyone does know of a documented incident, please let me know. And the video where some guys fill a car full of propane and ignite it doesn't count.

What I am offering: my experience with the conversion in case anyone is interested in doing it themselves.

worshipmentor

iTrader: (3)

You sound like a fairly educated "man" but let me clear up a few issues I have with your post.

"well if you found zero evidence, why do you think the EPA has banned all flammable refrigerants for automotive use?"
Besides the fact that I (and many other HVAC and auto air techs) dont TRUST the EPA, R-134a IS flammable!

"the compressor got damaged because of lack of oiling... pressures have nothing to do with it..." I have personally seen (back in 92-93 when conversions were in their infancy)the Nippon compressors blow the front off from the high head pressures of 134a. Granted it was partially due to lack of pressure relief because of the size of the condensor but these same systems worked well with 12.

"those "conversion kits" sold at auto parts stores are a sin to the automotive world... people buy them expecting they can just screw the adapters on, and just shoot a couple of cans of the 134a in and expect cold air... what most people don't know is R134a requires a completely different kind of oil... the original mineral oil WILL NOT WORK, it will just settle into the low parts of the system and do nothing... the compressor burns up as a result... " only partially true. We have successfully blended Ester oil with the existing mineral oil in many systems with no problems (how many people use "blended" synthetic oils in there crankcase?)

"the desiccants in R12 systems are also different," If this were true why are all of the reciever/dryers you buy today labeled R-134a/R-12 compatable?
The BIGGEST problem I have seen in 20 years of AC repair/maintenance/installation is leaking systems and an inproper vacuum. a vacuum isnt pulled to create a vacuum to put the refrigerant in. A vacuum is pulled and held to remove moisture from the system, PERIOD! to do a proper vacuum you need a micrometer that measure the moisture particles in the system. At room temp, water boils in a vacuum. That's the point. I have seen the bottom rotted out of a Mack truck condensor because of moisture. Mixing water with refrigerant creates an acid (hyrdochloric or hydrofloric). Even in minute amounts it is devistating to a system. Not only is the acid formed a problem but if there is sufficient moisture it can collect as ice particles in your metering device (think orifice tube) and eventually stop the flow of refrigerant.
The earlier post about getting some gauges and seeing whats going on FIRST is the best answer. Once you know that you can troubleshoot from there.

cody o

+1 to getting gauges. I apologize for letting myself get off topic.

The MAN

I respectfully disagree as far as the fittings goes
being an A/C certified tech, I had to know this studying for that stupid EPA section 609 test... yes, this means I can legally buy R12 if I want
honestly though, I hate to swing the "I'm certified" stick around just to make a point, but I'm saying this because the unique service port requirements is actually stated in the test study materials

there is zero need to flush mineral oil out of the system... this used to be the standard procedure in a conversion, but auto makers have found out this is unnecessary... like I said, the mineral oil just settles out in the system and does nothing... the ester or PAG oil you add in, will just do the lubricating instead... as I said already, most of the oil is in the drier/accumulator and the rest is in the compressor... so once you replace the drier/accumulator, whatever that's left in the heat exchangers and compressor are negligible to the performance of the system

if you read the TSBs from Toyota or the other car makers, they don't say to flush it... which means it's unnecessary and is a waste of time... obviously, it's better to do it, but it's not needed

The MAN

the 134a flash point is much greater than typical engine compartment temps... granted if your engine is on fire, there's more things to worry about than the 134a blowing the car up
the difference here is, the banned refrigerants have low flash points compared to 134a

also, I never said anything about oil blending or lack there of... you're just assuming from what I said that the mineral oil doesn't work that meant it's an issue with R134a... no it's not... you can leave it in there, but you must add ester or PAG oil and those oils will mix with the 134a and do the job lubing the compressor... the mineral oil will just settle out

cody o

Please don't take any disrespect, but being "certified" only means you can repeat what you've been told by one particular party. It's not the be-all-end-all of knowledge. Example: I built a circuit which my physics professor (Phd) said was impossible. He spend a week trying to understand how it worked, and another week showing it off to other professors once he figured it out. Point being, having a Phd didn't keep a lowly student from learning a principle he didn't know.

I don't think anyone is arguing the point that a conversion should be done properly. You can't mix R12 and R134a and expect your system to last very long. Not everyone has access to R12, that's why I'm offering this as an alternative.

Actually, the auto-ignition point for R134a is 482F, and 1627F for HC12a. Compare to gasoline at 495F. Please stop calling it a banned refrigerant; it is perfectly legal to use, if done properly. Unlike R12, which actually is a banned refrigerant. (Nothing wrong with R12, I'm just making a point: the EPA is a political entity and makes political determinations.)

In conclusion:
Hydrocarbon refrigerants are safe, legal, efficient, and inexpensive. If anyone can prove the contrary, I'm all ears. Until then, I will consider it an excellent alternative to R12 and R134a.

Team420

[QUOTE=The MAN;51745483

also, I never said anything about oil blending or lack there of... you're just assuming from what I said that the mineral oil doesn't work that meant it's an issue with R134a... no it's not... you can leave it in there, but you must add ester or PAG oil and those oils will mix with the 134a and do the job lubing the compressor... the mineral oil will just settle out[/QUOTE]

Converting a r-12 system to r-134a isnt all that bad for the compressor.... IF done CORRECTLY... The biggest problem with these conversions, is that people dont know what they are doing, and as explained above, yes, the oils and such are different, therefor, any time a conversion is done, you MUST have the system evacuated first, this means...it needs to be sucked clean, by a shop with the correct equipment to do this, failure to evacuate the system prior to conversion, almost always leads to a burnt up compressor....

No the r-12 oil will not hurt anything, but as quoted above, it will settle, and just take up space, leaving less room in the system for the lube's that do work, and adequate refrigerant.....

cody o

Here's a video on the "danger" of hydrocarbon refrigerants.

http://www.youtube.com/watch?v=DjtowzVzl_4

This group attempts to demonstrate that using hydrocarbon refrigerants can result in a cabin explosion. For the demonstration, they used the exact same refrigerant I put in my vehicles. Here are some issues I have with their experiment:

1) It is totally unrealistic. The were venting whole cans of refrigerant straight into the cabin. What on Earth would cause that to happen in real life? If the lines were severed in a collision, the gas would probably vent to the engine compartment (on the other side of the FIREWALL).

2) In order to achieve the concentration of refrigerant required for ignition, the cabin would absolutely reek of propane. That should be your clue to get out.

3) Don't light a match in a cabin that reeks of propane.

4) The man survived an all-out cabin explosion with nothing more than singed hands and a bump on the head.

I compare this to my experience with an airbag deployment several years ago, which put me in bed for over three weeks due to head injuries. In this case, the "safety feature" caused way more damage than the "deadly refrigerant". I would have MUCH rather been in a cabin explosion like this.

To be fair, R134a would do the same thing in that situation. Has anyone ever heard of this happening in real life?

I hope this sheds a little light on the safety aspect of using hydrocarbon refrigerants.

Matts90Runner

My R12 is putting out 40° with the old compressor.

worshipmentor

iTrader: (3)

Ive got 2 older cans (14 oz) of R-12 that I am not going to use (I like my R-134a thank you). If your into the R-12 and want some PM me and I'll sell them to you.

modlite

I spent $60 on ebay for 2 cans of R12. Replaced all the seal, evaporator, expansion valve, and put die in. Evacuated it, and filled it up. It was blowing at 22 degrees in 100 degree weather.

Needless to say 2 weeks later it leaked out through the low pressure line where it comes out of the firewall. Complete waste.

Going to just do the R134 conversion now, $10 a can, and I can check it at anytime with my own tools.

The MAN

just remember to change the drier and oil when you do the conversion