A/C leak/diagnostics

[JOHNFAK]

So its been winter here, and during this period my wife backed into front of my truck. Quite a lot of damage to hers, almost not a scratch on mine.

However summer is here an I go to put on AC and nada. So obvious thought is she damaged the AC condensor at front. 

I black light everything - cant see anything from the previous dye..... might be too old.

 

I vacuum everything down. It goes from 28HG to around 25HG in around 4 hours. So must have a leak.

So then I primed with compressed air to 100psi through high with system open (means both sides at 100). Couldn't hear any leaks. 

Sprayed with soapy water - that didn't do anything except make a mess of soapy water.

So I added some UV dye ...... and with the system still at 100 I started truck to try and get compressor to cycle and move some dye around and maybe see a leak.

Nothing ......(AC was cycling a few days back - just real often and not very cold).

 

So right now just a mess of dye, soapy water and still no idea of how to track down leak.

 

Surely there has to be a better way ....... ideas ??

 

*Side Note* When I started truck with 100psi in system the line between compressor and condensor got really hot. Obiously I never touch it under normal operation ....... so not sure how hot it gets ...... but seemed excessive.

 

[Mopar1973Man]

Remember compressed air isn't the same as freon so transferal of heat to cold isn't there. Typically the high side will be in the 150-190*F range with freon depending on high side pressures with freon.

 

I would at this point just stop by a NAPA store and get a o-ring kit and replace all the o-rings on the system. Fairly easy. Just make sure to lube all seals before inserting or re-coupling the line together. Make sure all them click too. Sucks to charge a system to have a unlocked line and blow the freon and oil out of it.

 

Oh.. My long chase on my truck turned out to be a bad compressor seal. After replacing the compressor all was good again. Never seen dye nor could I locate a leak around the compressor.

Edited April 4, 2016 by Mopar1973Man

[Haggar]

John,

 

Slow movement on the vacuum could be two other things.  Water in the system and bad vacuum pump.  When you reach the proper pressure temperature balance, the pressure will stay constant until all the water boils off (function of water surface area, temp and pressure.  Sometimes the water freezes off too, restricting how much or if any more will come out.  We have had to heat the pipes in large lines to get them pulled down.) 

Do a quick test on your vacuum pump (your oil could be low, or have a lot of water in it itself.) (we change our oil frequently.  Sometimes when its loaded with water, it can take hours for the oil to burn off all the moisture.)   See if you can pull a vacuum against your gauges.

 

100psi should be a good check, but compressed air has a lot of moisture in it.  so be careful.  We use nitrogen, and can go up to rated system pressure.  On the dodge I go up to about 300psi. 

 

Yes the outlet of the compressor will be a high pressure and high temperature gas.  As it exits the condenser, the pressure is maintained, but temperature should have dropped some, so that the gas will turn into a liquid. (of course this process is not right with air in the system.)  Compressor outlet temp can go to 200 F or so.  I think they use 225 as a max or so (trying to protect the valves and oil....)  Its hard to measure actual valve temp, but I would think it would be as much as 75 hotter than your measured area.  

 

Finding the stupid leak can be a total nightmare.  With commercial ac systems, we have a hermetically sealed compressor, and can usually see our condenser and evaporator.  With cars it becomes more of a crap shoot.  Sometimes I use a sniffer.  Sniffers are much cheaper now, and might be worth a look.

 

GL

 

Hag

[Mopar1973Man]

This why I typically head for the seal kit first typically like $10 to $15 for seal and not hard to change and might get the leak in changing the seals. Also during change seal check the sizes too. I've seen some seal kit include just a random assortment of o-rings so make sure you don't install too small of a seal. Another common mistake. Make sure to oil all the new o-rings do not install dry.

 

Don't use that leak stop freon.

 

Another weird thing that is rare but is there enough oil in the system. If it running low from leaking then o-rings might not seal up properly.

 

Funny I got called to the local body shop to look at a A/C system on a Infinity. It had been deer wrecked. Body shop had finish his work but need it recharged. I did find a leak in the system which was two fold. First the seals supplied with the condenser where too small and they were installed dry. After replacing with slightly bigger o-ring and pre-oiling the o-rings the was leak fixed. Sad the computer was screwed up and wouldn't start the compressor. Stupid dual zone computerized A/C.

Edited April 4, 2016 by Mopar1973Man

[JOHNFAK]

Mike you got the kit# for the seals. ?

 

Looking at this worst case.

http://www.amazon.com/AGPtek%C2%AE-Portable-Refrigerant-Detector-sensitivity/dp/B0088NW14O/ref=cm_cr_arp_d_product_sims?ie=UTF8

 

Cant charge with nitrogen - my compressor is a cheapy that barely will push 100PSI with any volume.

 

Worst case Ill fill up with r134a and uv dye and drive for 24 horus and try and detect. Or the leak detector.

Just dont want to start replacing parts to find out real answer. most are < 2.5 years old.

 

 

[Mopar1973Man]

Just go into a NAPA store and ask for them.

 

[JOHNFAK]

53 minutes ago, Haggar said:

John,

 

Slow movement on the vacuum could be two other things.  Water in the system and bad vacuum pump.  When you reach the proper pressure temperature balance, the pressure will stay constant until all the water boils off (function of water surface area, temp and pressure.  Sometimes the water freezes off too, restricting how much or if any more will come out.  We have had to heat the pipes in large lines to get them pulled down.) 

Do a quick test on your vacuum pump (your oil could be low, or have a lot of water in it itself.) (we change our oil frequently.  Sometimes when its loaded with water, it can take hours for the oil to burn off all the moisture.)   See if you can pull a vacuum against your gauges.

 

100psi should be a good check, but compressed air has a lot of moisture in it.  so be careful.  We use nitrogen, and can go up to rated system pressure.  On the dodge I go up to about 300psi. 

 

Yes the outlet of the compressor will be a high pressure and high temperature gas.  As it exits the condenser, the pressure is maintained, but temperature should have dropped some, so that the gas will turn into a liquid. (of course this process is not right with air in the system.)  Compressor outlet temp can go to 200 F or so.  I think they use 225 as a max or so (trying to protect the valves and oil....)  Its hard to measure actual valve temp, but I would think it would be as much as 75 hotter than your measured area.  

 

Finding the stupid leak can be a total nightmare.  With commercial ac systems, we have a hermetically sealed compressor, and can usually see our condenser and evaporator.  With cars it becomes more of a crap shoot.  Sometimes I use a sniffer.  Sniffers are much cheaper now, and might be worth a look.

 

GL

 

Hag

 

Added new vacuum oil to the vacuum pump prior as it was low.

 

You mean try and pull vacuum against guages with guages shut off - and see if it drops also ?

 

Yeah the high prssure was really hot out of the compressor to teh condensor. But obviously as you said its with static air and I never bothered to see how hot it gets anyway with freon ....... but was quite hot to touch ... would have to guess 200 F like an oil pan

 

 

 

 

 

[Haggar]

John,

 

You saw the low oil...  darn was hoping that was it.  (I have gotten bitten by that too many times to list.)  Yes just test your rig sort of.  Screw the low side to a valve you can close, and pull through the center and make sure your gauges are reading and your pump is really working.  I have added short extensions with valves to my set, trying to minimize freon loss and air entrance during disconnecting.  I have to test my stuff first since I don't use them on a daily basis anymore.  they hang around the shop and get dropped and fiddled with much more than actually used anymore.  see if it is something weird in your gauges (if your gauges leak down, you can't help but think the car might be doing it.) 

 

I am pretty sure I misread your post.  I thought you were seeing a rising pressure while still vacuuming.  (that is what I imagined in my brain)  but you were hold testing.    I don't trust the vacuum hold test. (too hard to trouble shoot really, and the shaft seal leaks anyway...)  Go with a pressure test.  run it up to 300 or so. (our high pressure doesn't trip until 450 to 490, safety valve is north of 500 IIRC)

 

Hope you find it!!!!!   I am still searching for mine....   I lose about 12oz a year and have not found it yet...  never shows up on a static test.  (vacuum or pressure or sniffer....  i get a hit occasionally on the sniffer,  but no more than running around in the shop with it.  nothing saying "bingo here stupid!")

 

Hag 

[JOHNFAK]

LOL.

Ill give the vacuum a go on the guages alone.

Asides that Ill pull the compressor and check the oil there. 

 

Anyone know if you can just add UV dye to the PAG oil. I dont see why not. 

Normally I add to the lines ...... but its way messy.

 

If I cant detect the leak Ill see how long it lasts with ~3 cans and decide on buying a sniffer from there.

 

 

 

 

[Haggar]

John,

 

I don't see why not at all.  Should not make a difference. 

 

I hope you find your leak!  maybe mine will be in the same spot!  got my fingers crossed for you.

 

Hag

[Mopar1973Man]

I had two different shops and myself hunting for my leak like I said mine happened to be the compressor front seal. As for the others I've dealt with like I said a seal kit typically rules out all connections which is a come spot to leak but hard to spot. As for adding dye I buy a 5 shot dye can from NAPA. Just hook it up to the low side hold for about 2 seconds on the trigger. Load it up with freon much cleaner and easier to deal with.

[JOHNFAK]

Dang expensive son.

 

http://www.amazon.com/FJC-4910-Universal-Fluorescent-Detection/dp/B002AII980?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o05_s01

 

 

[Mopar1973Man]

Not always will you have the pleasure of opening up a system to add dye. At least with the can I do not have to open the system. I can add dye without having to pull a vacuum and wasting exist freon. Might be expensive but lots easy that the bottle you posted. If you system is dry then I would uncouple the low side line at the accumulator and pour it in the line. Couple back up and recharge. Remember I work all makes and models of vehicles with A/C so can stuff is universal and easy.

[IBMobile]

How about dumping a can of this in?http://www.oreillyauto.com/site/c/detail/INTC/R134AUV12CA.oap?ck=Search_134a+with+uv_-1_2902&keyword=134a+with+uv

[Mopar1973Man]

Basically the same stuff. I like those too but those are a single shot can. Once the top is punctured your committed to discharging the entire can before you can remove it from your freon hose. That why I like the 5 shots over the singles. For John purpose it would work. 

[JOHNFAK]

Didn't realise your can was a 5 shot ...... makes the pricing better.

 

Filled her up tonight with 3 cans .

65 ambient 

35 low

175 high.

 

Was blowing cold ....... well see how long she lasts.

Will blacklight again tomorrow night. 

 

[IBMobile]

1 hour ago, Mopar1973Man said:

Once the top is punctured your committed to discharging the entire can before you can remove it from your freon hose.

Not so fast Kemosabe.  The special California can has a valve in the top that shuts the flow off when the can is disconnected so you can put in what you want and save the rest for later.  You need to use the thread on adapter to mate the can to the A/C gage fill hose. 

If you live in CA you get to pay a $10 a can deposit and if you don't turn in the empty can in 90 days you loose the deposit, the state keeps your money.  I bought a case of 134a cans in Las Vegas, same cans as in CA but no deposit required.  I use them now for my refund. 

[oldbeek]

On ‎4‎/‎5‎/‎2016 at 8:27 PM, IBMobile said:

Not so fast Kemosabe.  The special California can has a valve in the top that shuts the flow off when the can is disconnected so you can put in what you want and save the rest for later.  You need to use the thread on adapter to mate the can to the A/C gage fill hose. 

If you live in CA you get to pay a $10 a can deposit and if you don't turn in the empty can in 90 days you loose the deposit, the state keeps your money.  I bought a case of 134a cans in Las Vegas, same cans as in CA but no deposit required.  I use them now for my refund. 

Shame on you. A 134a smuggler. LOL