a/c question about leaks

[thor1701]

i have a leak in my system, charged it after replacing the low pressure valve as the core in the old one got stuck and was letting everything out, now a few days later, its completely empty, anyways my question is, im going to buy a black light and some uv glasses, and buy a can of 134a, how long do i have to keep the truck running with the a/c on to detect any kind of leak, also where should i be looking? i dont know if i can see the parts behind or in front of the radiator, depending which way you are facing
i have a 96 4.0 L v6 explorer

 

[fixt]

It doesn't have to be running. A little R134a will pressurize the system based on ambient temperature. Or maybe it does to circulate the dye, not sure how that stuff is circulated through the system. Maybe someone will clarify thats used it.

I'd pay attention to low and high pressure valves, and then look at every place its o-ringed, and around the accumulator/drier. Just trace out the lines and look.
Make sure your valve caps are in good shape too.

 

[thor1701]

yeah i would assume it had to be running because you always put new stuff in while its running, i just want to know how long should i keep it running before i can start to look for the leaks with the light and glasses

 

[radman]

Let it cycle about 20-30 minuets to get the dye to circulate through the entire system. If you have trouble locating the leak you may have to wait longer.

The most prone spots are the shrader valves at your charge ports, the "O" rings at the pressure cycling switch and any hose couplings using "O" rings. If they all appear good then you will want to go under the car and find the water drain hose that allows moisture from the evaporator to run out of the heater box, if it is leaking there it will carry some dye with the water.

If it is a large leak you may be able to hear it hissing after the engine has been shut down for a few minutes. There will be some noises right after shut down but that is normal, the system is equalizing the pressure in both sides (high and low) of it's self.
Mike

 

[thor1701]

i got a little can of a/c stop leak & detector, but im not sure which to put in first, that or the can of 134a, i might just go to autozone and pick up a set of o rings and just replace the one's on the low and high pressure switches, i replaced the switches last year but cant remember if they came with o rings or not

 

[radman]

thor, Most 'o' ring leaks are easy to spot as the refrigerant will always carry out some oil along with it. If it has been leaking for some time dirt will stick to the oil and have a wet greasy look.
Mike

 

[thor1701]

is there a place somewhere on the web that list's where all the o rings are for the system? i just got a pack in the mail and want to replace the one's i can get easy access to, i know there's the two at the back of the compressor, i think there's a few on the low and high pressure switches, is there one at the low side pressure port? and do i have to do anything to the compressor o rings, like put a little oil on them or something? or do they go in dry?

 

[firepop5]

There are o-rings at every connection in the system:

Compressor to high pressure hose
high pressure hose to condenser
condenser to hose that leads to evaporator (and on orifice tube)
evaporator to receiver drier
receiver drier to low pressure hose
low pressure hose to compressor.

There is also an o-ring at the pressure switch on top of the receiver drier. Coat new o-rings with proper refrigerant oil.

How long it takes for the leak to show up depends how big a leak there is.

My 96 had a leak on the aluminum tube going into the bottom of the evaporator. It is clamped in a metal bracket, and the aluminum corroded where it came in contact with the black metal. I spliced in a small section of tube after cutting out the corroded aluminum. This repair lasted 2 years before it started to leak again. Then I replaced the evaporator and no problem since.

Are you using gauges to determine the system is empty?

 

[thor1701]

im using one of those gauges that came with a retrofit kit i got some years ago, and its dead empty lol
so im assuming the refrigerant oil is the pag oil?

 

[drdoom]

Don't add the stop leak, just the dye. Look at the accumulator, the steel ones with the insulation foam all rust out.

 

[imp]

How Spliced?

There My 96 had a leak on the aluminum tube going into the bottom of the evaporator. It is clamped in a metal bracket, and the aluminum corroded where it came in contact with the black metal. I spliced in a small section of tube after cutting out the corroded aluminum. This repair lasted 2 years before it started to leak again. Then I replaced the evaporator and no problem since.

Are you using gauges to determine the system is empty?

How did you do the splice? Hose? Aluminum tubing welded in place? This repair would likely be beyond the ability of even the better A/C shops. imp

 

[radman]

Oil?

thor,
Your car requires 26.08 oz. of 134-A and 7 oz. of Pag oil on the complete system.

 

[firepop5]

To do the splice repair I bought a brass double compression fitting, the type that uses a ferule on the tube. Something like this:

http://www.righttoolusa.com/p/5-Bra...5339640.html?gclid=CNbSv6T5_bcCFUue4AodZzsA1w

It was about 2 inches overall length. I cut out enough of the corroded tube so when the fitting was installed, the tube's overall length was the same. The splice was on the lower tube going into the evaporator just after the part that contains the orifice tube. The repair held for about 2 years until the tube corroded just beyond the splice. Replaced evaporator then, and no problems since.

 

[thor1701]

so no one's answered my question, which should i put in first, the dye or the 134a, or does it really matter?

 

[radman]

You can buy the refrigerant with the dye already in it. If you can not find it together then put the dye in first while the pressures are low.
Mike

 

[thor1701]

well i had put the dye in, then the 134a, ran it for about half hour, no dye anywhere, so i took it to a shop, turns out whoever had the truck before me tried to do something with the high pressure line and the fittings were not correct or something, so got that part fixed, and for some reason the low pressure switch does not fit nice and snug onto the thing like it should, but somehow he got it to work, so now it works, but...he told me i need to take the radiator out and backflush and clean out the condenser, i guess there's not alot of air flow so its making the high pressure go up, not something i look forward to doing, luckily i have experience in taking them out, not fun, just wish there was a way to do it without doing all that work, i will have to wait till this heat wave is past here in fresno ca, im not gonna kill myself doing auto work in this heat