I have a leak in my A/C system. It is completely discharged. I bought some o-rings from my Ford dealer, but the system does not hold a vacuum. Is there an o-ring kit available somewhere so I can replace all of the o-rings in my a/c lines?

 

Check Rockauto, O'Reilly, etc. for a system O-ring kit for your truck. They are in the $5 - $8 dollar range. Besides O-rings in the kit, they usually have some garter springs for Spring-Lock couplings on vehicles that use them.

For a 1997 F-350, it probably is a kit like for my 1994 Bronco. Lots of O-rings, more than needed for my application, but that's OK. I found the hardest one to match up was the O-ring that fits between the Accumulator/Drier and the Evaporator core. There were other O-rings that were very close in diameter and thickness, and the old one was well-flattened, which made it harder to figure out.

If you have been unable to pin-point a specific leak point, putting one 12 Oz. can of R-134a in to give it pressure can help. Lot easier to find a leak with pressure.

But it IS possible to have a vacuum-only leak, that will not leak under pressure. A common place for one of those is the service port Shrader valves themselves, when no hoses are attached. Sometimes all it takes to fix one of those is to snug the valve core a bit with a valve core tool.

 

Anything fitting can potentially leak, they have a service life and more often than not its the small things that cause the most trouble.

Every time I've had a new-to-me vehicle's A/C serviced I've replaced both Schrader valves AND the caps for those service ports. All four pieces should cost less than $30 even from the dealer but its an expense well worth making.

 

Thank you. I did pressurize the system by adding a can of R134a. That's how I found the leak. I found a split o-ring on the left side near the radiator/condenser. I replaced that o-ring, but the system won't hold a vacuum. I think I got the wrong size o-ring. The "old" one is green; the Ford replacement is black. I didn't try using two o-rings, but that doesn't seem like a good idea to me. I'll check on those o-ring kits.

Is there a part number associated with this kit?
Is it a "standard" o-ring kit full of differently-sized o-rings?
Do these o-rings need to be oiled?
Do they need to a have temperature rating?

I know it's winter, but I'd like to have this fixed before summer arrives.

 

I looked it up on Rockauto, the 4 Seasons kit #26721 is what I think I used, looking up a 1997 F-350 shows the same kit used. I would not use a 4 Seasons compressor, but have not had trouble with their other stuff.

It is a kit tailor-made to Fords of certain vintages. It will have more parts than you need, but it is not some grab-bag of misc. parts.

Yes. They should be oiled with the refr. oil spec'd for the system, or Nylog of the proper type for 134a. I used refr. oil, as I had that handy for the total system replacement I was doing. I still have a plastic bottle of the original R12-compatible Nylog laying around. Nylog sometimes is referred to as "super snot". It is the stringiest stuff I have ever seen. Its claim to fame is super-sealing. I think I bought it online from ACKits.com

Using R-134a - compatible O-rings made for AC work should take care of that.

When R-134a came out, O-rings were green to differentiate them from the black R-12 mineral oil compatible O-rings that had been used for years. I saw some red ones in a Dodge from the factory once.
I would feel most comfortable if they were green, though I have heard of some using black now, but of the proper material. I would expect auto manufacturers to have a tight hold on their supply chain, so they will be getting the right composition O-rings no matter what color now.
HOWEVER, I don't think that tight control exists in the after-market!
If you got the O-rings from the dealer, in a SEALED original plastic bag, with a more recent Ford part # imprinted on it, then they may be OK. But if some parts guy just went in the back room and came back with some O-rings in his hand, I would not trust that at all!

 

Thank you for the information gang. Any idea what the difference is between the MT2526 and #26721 kits? They both show the same generic photo.

 

I replaced the o-ring on the high-pressure side and the system is holding vacuum. The system is completely empty and should hold 38 oz. I started charging with the DIY R134a cans (20 oz) from Walmart. The gauge showed the system pressure going into the "red zone" before the first can was empty. The system should hold nearly two cans of refrigerant.

Has anyone used these recharge cans before? I don't want to overcharge my system, but I also don't understand why the pressure gauge is reading in the "red zone" with less than one can of refrigerant in the system.

I want to charge the system with the proper amount, but don't understand why the gauge that came with the refrigerant shows an overcharge situation. Since the A/C system was completely discharged, should I ignore the included gauge, and install the indicated system amount of 38 oz? I'm assuming the included gauge is not accurate.

 

The compressor probably isn't running so the pressure in the can has pressurized the system up to the limit of the can's pressure.

Pressure should be somewhere around ambient temp in °F * 1.1. Give or take a bit...

Now you need to figure out why the compressor isn't engaging with a pressure of more than 45 psi.

 

I see the wheel cycle on and off. Is it possible the compressor was damaged? Can I replace the wheel/clutch by itself? Or is better in the long run to replace the entire compressor, if needed?

 

Is the compressor coming on and staying on or is it "short-cycling"?

If it's short-cycling, that's normal because there isn't enough refrigerant in the system yet. You have to be patient and allow the compressor to draw in the gaseous refrigerant. As more and more refrigerant is drawn in, the on-time for the clutch will lengthen and you will see the low-side pressure gauge drop with each on-cycle and rise back to static with each off-cycle.

 

It is short-cycling. My concern is the pressure reading on the can gauge going into the red zone before the first can is empty. If I'm understanding what you're saying, as the system runs, the cycling will get longer as the gas in the system is circulated? And I can continue adding the rest of the first can and a good portion of the second can? Is that right?

I thought the refrigerant in the system is a liquid, is converted to gas, and condensed back into a liquid while the system is on and cooling the cab.

Do I disregard the can's pressure gauge and add the amount of R134a listed on the sticker? Remember, my system was open at one time, so there is no R134a in the system, except for the half-can (10 oz.) I added the other day.

 

Yes. Ignore the gauge. Using a singe gauge is like trying to listen to a stereo with one ear plugged.

If you have the can upright, the refrigerant is evaporating in the can and being drawn into the system by the suction side of the compressor as a gas. The evaporation in the can is why it gets so cold.

Now, if you briefly tip the can upside down, liquid refrigerant will be drawn in. However, this runs the risk of causing the compressor to slog since it's not intended to receive liquid to try to compress. Do not do this unless you wish to risk replacing the compressor yet again.

Just be patient, it may take 10-20 minutes to empty a can as a gas. Warming the can in a bucket of hot water will help speed it up.

 

Thanks for the clarification on the recharging process. I'll give that a try. Should I be concerned if liquid refrigerant entered the system? It's been several days since I initially started the recharge process. I assume any liquid inadvertently introduced to the system would be in gaseous form by now, correct? I should be able to put in the rest of the first can and continue filling with the second can, correct?

 

When my ac system failed it was from ac pump faliure, beacause the previous owner did not use the truck in the winter months, so when i had it filled up with r-12 and lubrication media at the ford rated specs. The motor ceased up after 14days aprox. When i talked to the ford van mecanic he said that in order to sucsessfully convert the ac system to r-134 i would need to change the ac motor(w.Clutch) I know for a fact that som of the orginal ac motors from ford is not compatible with r-134 possibly due to the lubrication media?, And there ar 2 types of orfice tube aka the filter inside the metal hose going to the ac element inside the heating/cooling unit. Too bad i didn't take pics, it was clogged with metal filings btw.. so important to check!!! when you first change things..
And I also needed to take apart all the plumbing and change to green o-rings witch i bought from rockauto btw. Since i live in norway and they are the cheapest to get parts from, for me. I was also reccomended from ford to change the ac Receiver Drier / Accumulator beacause the oil in the old system would clump up and aventually clog the new system if i did not, bacause the r12 lubricant/oil and the r134 lubricant/oil is different btw. And is NOT compatible with each other i was told from the a/c specialist at the ford dealership dont know if it was so they would make more money or not, i just know that you have to be a ac gas specialist here in norway to change/do alterations to the ac system, not like the us where you could go to wallmart and by a can of r-134 and top up the system yourself..
Worked flawlesly for 1year now even at winter times, im a truck driver and we ar recommended to use the ac atleast 1our in 14days period so the gaskets/pump dont dry out so i do the same with my 1993 e350 7.3 idi

 

Welcome to the FTE, polarbear87. I'm not converting my system to R134a. My system is R134a from the factory. What vehicle did you have to convert? It is true, the R12 and R134a refrigerants are not compatible.

I had an o-ring on the high-side split awhile back. The system vented and depressurized. I finally replaced the o-ring and pulled a vacuum on the system. It seems to be holding vacuum. I just need to recharge the system with R134a. I was concerned about the high pressure reading on the gauge that came with the can. I put in less than half a can of R134a and the pressure was reading in the over-pressurized area. I wanted to be sure I could disregard the can's gauge and fill the system with the 38 ounces needed.