hi all. I have a 90 f150 xlt 5.8 auto. my ac blows warm. my clutch kicks in and out. out 7seconds in 1-2 seconds. I bought adapters to hook my a/c guages up to it(i am assuming it still had freon-r-12) i have added nothing to it i bought it used. any way my guages read (motor off)static +6 low side,40psi high side(its about 45-50 degrees here) with motor running and ac on low side goes up to +10 and then drops to 0 when clutch cycles. high side still about 40-50 psi.(no valves open on guages) open the guages and low stays at +11 even when clutch cycles and high side is about 45 psi. My guages are for 134 no r12 . any way am i just very low on freon? any help is greatly appreciated. thanks.

 

In short, the answer is yes. the clutch is cycling do to the very low pressure on the suction side of the system.I would recomend that you recover whats left and recharge with r-12. However, if you decide to retro to r-134a, search this forum for tips and hints. good luck

 

thank you for the input. I will probably do that(convert). I bought a vacumm and i have the gauges, im thinking it would be cheaper to do that than have a shop put r12 in(if any shops still do that). Do i need to evacuate the system in order to put in 134? or can i just put it in? Ive been reading alot of confusing things. does any one know if i can just add 134 to my system without having to change anything or evacuate anything? thanks.

 

You need to do a little more than just add refrigerant. The first issue is finding the leak and fixing it. It's likely an o-ring in one of the spring lock fittings.

To do a good conversion:
- Have the remaining R-12 recovered, if necessary.
- Flush the Evaporator and Condenser with solvent and lots of compressed air (lacquer thinner works well) to remove the old oil.
-Drain the old oil from the compressor. "Flush" the compressor with the new oil.
- If you see oily residue on the bottom of the compressor or on the clutch face the compressor is leaking. Shaft seals and body seals are common leak points on that compressor. The shaft seal can be replaced if necessary.
-Replace all of the o-rings on all of the spring lock fittings and the rear of the compressor. It's ~$5 and is cheap insurance against leaks later on. Don't forget the one on the cycling switch.
-Replace the accumulator. This is important!
-Replace the orifice tube. It is either in the Evaporator inlet pipe or integral to the liquid line. (small line from the condenser to the evaporator).
-Install quality STEEL conversion fittings. The cheap aluminum fittings are prone to leaks.
- Add the recommended amount of oil to the system making sure to add about 2 ounces to the compressor. Ester or Double End Capped PAG oil is recommended.
- Evacuate the system with your vacuum pump for 30-45 minutes and make sure it holds 28" of vacuum for 15-30 minutes.
-Start with about 80% of the original R-12 charge amount. Use only virgin R-134a, no sealers or performance boosters. UV dye is a good idea.
-After you get 80% of the original charge amout in, add refrigerant a couple of ounces at a time until the evaporator inlet and outlet are at the same temperature and suction line is cool all the way to the compressor.
-You are "supposed" to add a high pressure cutout switch to a converted system. That's your judgement call.
If you do it this way, you will likely not notice much difference from R-12. These trucks convert really well if you do it right.


A couple of notes:
-You can adjust the cycling switch to bring the low side pressure down a bit for R-134a. Turn the screw clockwise, no more than 1/2 turn.
-At 17 years, your fan clutch is probably weak. This will kill the AC performance at low speeds and cause the high side pressure to be too high.
-The low side pressure is roughly equal to the evaporator temperature. (1500 RPM, Max AC setting, blower on high and doors open)
-Rule of thumb for the high side pressure is about 2.5 times ambient temperature (1500 RPM, Max AC setting, blower on high and doors open).
-Don't be tempted by "conversion kits". The fittings are poor quality and there is nothing else in them that you can't buy separately.
- Use regular cans of refrigerant and a can tap. Cans with a hose attached push air into the system. That little bit of air can make the difference between a system that works and one that works well. Make sure to bleed the air out of your gauge hoses too.

Think about this. If you reseal the system properly and replace the accumulator, you should not have to service it again for many years. The "high" cost of R-12 will be spread over that time and is really not a major expense. R-12 is what the system was designed for and will give the best performance. For $25, you can take an online test to be certified to buy R-12. It is about $8-10 per pound in 30lb containers, the small cans are higher. Just something to consider.

Good Luck

 

Great advise, I think that i might try to clarify one thing. when you replace the oriface make sure you use the red one, not the green.

 

why should you use a red and not green orifice tube? this truck is 17 yrs old and in excellent condition. I do not understand why i should replace all those parts. granted that is probably the correct way (and more exspensive) but if you can get a few years out of it by just removing the r-12 and installing 134a why not do it? so what if it leaks back out in a month or two or longer. i will just add a can of 134a. summer around here(toledo ohio) is only 4months long anyway.ive read quit a few posts where people didnt do anything but ad 134a and they have little or no problems.anyways i just did it today. I drained out any r12 that was in it and hooked up guages and put in 134a. says it takes 3lbs 8oz of r12 so i put in 28oz of 134a. its 70 here today and at idle its 58 degrees in the cab. my high side was 175 to 180 and low side was around 27. now on cycling it was 11 then go down to 5. then it stayed at or near 11 and the clutch would stay on for 15-20 seconds and off about 3-4.I ran out of 134a. I will check it tommorrow and see if i need any more 134a. I dont expect it to get down to 36 degrees or so , so if i can keep it at or near 55-60 it will be cool enough.

 

Well, now you have an AC system that is not cooling anywhere near like it should, with mixed refrigerant, leaks, the wrong oil, likely air in the system, an old accumulator desiccant not made for R134 that can now rupture... I see a trashed compressor in your near future. But you did get off cheap...

 

for now.. as Irsx101 said, you most likely have got air in the system and with air comes moisture. Moisture and the old r12 oil forms a nasty acid that will eat your most all your rubber parts. so now you have dug yourself a good hole. so WHEN that compressor granads, you are looking at a good repair bill.

 

I have read up on some of this so called bad stuff that will happen when you just add 134a to a r12 system. I did get rid of most(as much as i could) r12 before adding the 134a.Any way some of what ive read stated that the newer refrigerant will not cause problems with the oil. It was the older 134a oil that would clog it up. Also there has been no proof that o rings are not compatable with 134a. And a lot of people have been saying they just did what i did and have had no problems for years. Maybe i will and maybe i wont. again so what if i have a little leak? i will just put more in unless its a big leak then i will fix it. I would expect it to leak out after 17 years any way(its a 1990) hell even a tire will lose air after a while ,should i replace the rim? cmon.maybe my stuff will take a dump tomorrow or maybe not ,by the way how did i get "air" into the system?and yes maybe its not cooling as well as it could (or did) but 134a doesnt cool as well as r12 anyway,and besides i also didnt add enough 134a yetonly 28 oz or so probably not even that much.Its supposed hold56oz of r12 so ive only added half that(i know it should only take 80 percent of r12)so i can still add 1 more can(14 oz) and that will be roughly 75 percent of r12 and MAYBE that will let it cool down even more. I dont know. If it doesnt THEN i might try to do it another way.

 

It's your truck. You are allowed to do with it what you will. You asked a question, got answers, and are now telling us how we're wrong. You knew what you were going to do in the first place, so why bother asking? Our answers aren't what you wanted to hear so you read around until someone wrote what you wanted to hear.

-The problem with the oil is that the R-134 will not carry the old mineral oil through the system, thus starving the compressor for oil.
- There are no compatability issues with the o-rings, they are just 17 years old and cheap to replace in the spring lock fittings that are notorious for leaks.
-When the system is low on charge, air is drawn into the leak by the natural expansion and contraction of the gases left in the system due to temperature. There is also air in the charging hose of each can of R-134a that you used. It only takes a small amount of air to raise the head pressure enough to damage the compressor.
-If you had a leaky tire, I wouldn't expect you to replace the rim, but I would expect you to fix the leak and replace the $1.50 valve stem if it was 17 years old.
- In these trucks, R-134 will certainly cool as well as R-12 IF the job is done right.

I certainly hope that your attitude about the AC doesn't carry over to other maintenence areas. If so, that "excellent condition" truck won't be for long.

 

first of all i NEVER said you or any one else was WRONG. I merley said what i have read. And yes your opinion is and knowledge of the ac is greatly appreciated. I did not mean to sound like i was a smart azz or anything i was only trying to ask why on some things that you and others have pointed out. I only have gotten how much damage or how wrong it is to do what i did but when you read other posts its saying thats bull crap it doesnt matter. Thats why im confused. For example on here under tires etc some people seem knowledgeble and they said 35 in tires on stock 8in rims needs at least 6in lift and some said less and shim the bumper etc etc. well i put 2.5in lift in and they fit fine (a litle rubbing at full turn but thats expected) no bumper shimming no special rims nothing lots of room. Any way i was only looking for IF it would work without changing everything over (the cheaper and easier way) Just like you said to buy the red orifice tube not green i only asked why? what does the color difference have to do with it(i know its internal probably but i was just wondering) i am sorry if you or anyone else felt like i was dissing them. Any way i removed the freon i put in and drew vacuum for 25min today i am going to do at least most of what was recommended to do i just hope i didnt do any "damage" in that short of time. (i never drove or started it after i did that) . Thanks to all.

 

There is a lot of anecdotal evidence online about various things people have done and gotten away with it. You may find some who just charged the system with R-134 and it worked. I see people nearly every day that it didn't work for. What seems like a cheap fix turned into many hundreds of dollars. It's the same with R134a retrofit kits. For every person that says it worked for them, I see 5 that it didn't.
I don't like seeing people spend $20-40 to avoid a $200 repair that will now cost them ~$1000. I like making money, but not like that. Think about this; If AC repair could be done that cheaply and be reliable, I would not have a job.

Ok. Since you've dumped the charge, take a few minutes and about $15 to do a few things that will give you a fighting chance.
-Get a set of Spring Lock Coupler tools (loaner from the parts store). Separate all of the fittings and replace the o-rings. Replace the 2 at the rear of the compressor. It's really easy and cheap.
-Get 8-10 ounces of Ester based oil. Remove the compressor and drain the oil out. Add back about 2 ounces of Ester oil. Remove the accumulator and drain all of the oil that you can. Add back about 3 ounces. (You really should replace it, but...). If you have a compressor, blow the oil out of the condenser, evaporator, and lines as much as you can. Add the remaining oil where you can. You want at least 8 ounces of the Ester oil in the system. The old oil just takes up real estste in the system. (You really should flush, but...)
-Replace the orifice tube. The red one is slightly smaller and is said to work a bit better. I personally never saw much difference but maybe bustech81 has. It's also a filter screen and the old one will have some debris in it.

You mention having a vacuum pump. Do you have a gauge set? If not, you can rent\loan from a parts store.
Pull a 29" vacuum on the system for at least an hour. Charge about 80% into the system making sure to bleed the air out of the lines between cans. (Not an issue with a can tap and regular cans). Add more a couple ounces at a time until both evaporator tubes are the same temperature (1500 RPM, Max AC, High Blower, doors open) and the suction line is cool back to the compressor. The high side pressure should be about 2.5 times ambient temp, the low side pressure should be as close to 30 as possible. You can adjust the screw on the cycling switch to tweak it a bit.
If the outlet temperature goes up at idle, your fan clutch is probably bad. It's really common on these trucks.

Although this isn't the greatest way to do it, it's pared down to the bare minimum. You will have a decent chance of the system working good without damage and frequent topping off.
Good Luck

PS. My conscience insists that I say this," You really should do it the way I outlined earlier".

 

Again thanks for all the input. Wow that is alot to comprehend all at once. I understand what you mean when you said if it was easy you wouldnt have a job. So i take it you are a ford /ac mechanic or something along those lines?I was at the parts store today and saw that they sell flush,and a couple kinds of oil and a couple kinds of 134a(the ones i used the first time came in the kit) didnt realize how much stuff they have.Yes i do have guages(brand new-34bucks at harbor freight) a vacuum and lots of tools including a compressor and welders and torches.(lets hope it doesnt get that bad-ha ha)its funny how the "kit" said to just remove r12 and recharge(guess they want to sell you ALL new parts a little later huh?)would it be worth getting any of the above mentioned parts from a junk yard or not? and also would new/used parts designed for 134 even fit onto my existing equipment?(lines, etc)and roughly how much for the parts that you would recomend replacing?does auto zone carry most?

 

Most of the stuff on that display rack at Auto Zone is designed to do 1 thing, flush your wallet. It's mostly made by a company called Interdynamics. All of the sealers, boosters,additives, etc. are snake oil, just like most other stop leak and engine\trans additives. The quality of the gauges, fittings, and other hardware is dismal. Their instructions, or lack thereof, gives the impression that "all you need to do is connect this hose....". Most of the time, when I see a crashed compressor there is usually an Auto Zone receipt for ID products somewwhere close by. The flush cans work pretty good, but you can do just as good with an air compressor and lacquer thinner. Their can taps work well (The brass one with no hose). There IS some good stuff on that rack, you just have to be careful.
The parts (accumulator, orifice, etc. ) from Auto Zone are fine.
If you have all of that equipment and tools, you are good to go. Here's a list with approxomate prices.:
Accumulator- ~$28.99 9(AZ, part #4218)
Brass retrofit fittings- ~$10 (NAPA) The aluminum Interdynamics fittings are very prone to leaking.
Oring kit- $8.99 (AZ, part # MT2526)
Ester oil- ~$6
orifice-~$3
can tap- $5.99 (AZ)
Spring lock tools- $5-20 depending on which ones you buy. The clamshell type work best. AZ may even loan them.
You'll need refrigerant, of course. Get the pure R-134a, no sealers or additives. Get one can with UV dye, I think it's $1 more per can. That way, if you ever have a leak, you can find it easily with a black light.

You can do the whole job for less than $100 and, barring a compressor leak or blown hose, it should last the life of the truck. The only other expense may be a fan clutch, ~$60. The parts you are replacing are wear items, so used stuff isn't a good idea. Used hoses are a judgement call. I think the later condenser for R134 will bolt right in. Used is ok as long as there is some charge left in the doner truck and it's not physically damaged.
Written down, it looks like a lot of work, but it's really not. You'll see once you get into it. Doing it this way, you should be able to get vent temps in the high 30s-low 40s.
That Harbor Freight gauge set is a good deal for a DIYer. If you look at their site, they also have a flush gun for about $25 that works really good.

Since you asked: I was a Ford Master Tech until 2001. I changed careers and went into Information Technology 7 years ago. I have a part time business doing MVAC service and electrical work on collector cars, bikes, ATVs, etc. I got fed up with working on cars, but I still can't keep my hands clean
Good Luck, and if you need anything just yell.

 

thanks alot for all the info,seems you really know what you are talking about. i will keep you informed.