3rd gen A/C leak..Where are the common places that they leak.
 

Hi Guys, I have been having to recharge my a/c system pretty often. I have a leak somewhere and its getting worse. At first would loose the charge over six months. Now it will leak out over 3 weeks. I have done some soapy water tests under the hood but no bubbling. I admit I am not able to to get to all joints because some are plain difficult to get to.

Where are the 3rd gen most likely to leak?

Mine had a leak at the pressure switch. It was on the bottom so I would not see the bubbles when doing a soap test.

Have you tried using the UV dye?

my evaporator went out recently. not sure if its common, but it definitely started out as a small, almost unnoticeable leak. it now hisses in the dash and there's refrigerant residue on the inside of the windshield. stopped using it till i can get a replacement.

cptpain is on it. If you haven't done it already, next time you recharge, pick up a dye kit at autozone/advance auto or wherever. A lot of recharge kits actually contain dye (considering a non-leaking A/C should not need to be recharged). Then all you need is the UV light. Just look for the rave party going on in your engine bay. ;)

Actually come to think of it, unless you've done a 134a conversion, you'd probably have to get a dye kit by itself instead of a 134a + dye kit at an auto retailer. That is unless they sell the 12a refrigerant + dye online.

System o-rings, compressor shaft seals.

Compressor shaft seals seem to be nearing the end of their lives at this point in time as well. You'll sometimes see "sling marks" of refrigerant oil on the hood or frame rail in line with the compressor pulley. Also check and see if the inside lip of the compressor pulley is oily/gunky. My car did both.

Leaks usually manifest themselves as dark/oily spots on heat exchangers, and just generally greasy/dirty spots at system joints.

If you still can't find any evidence, add dye then look around and see what you can see. Check the evaporator drain tube for traces of dye as well....although if you live somewhere hot and dry where the system will generate very little condensate, you can have an evaporator leak but not see any dye.

mine leaked at the expansion valve on the evaporator, put in a new valve and orings and done.

Do yourself a favor and replace all the o-rings. Order them from Malloy Mazda. Should be less than $60 for all of them. Its a lot easier to do with the engine out but you can get to them. pick up a 134a retrofit kit at the autoparts store. R12 is expensive and you will waste a lot of money if you have leaks . Evacuate the whole system and pull vacuum for at least half an hour to get all the moisture out. Make sure it holds vacuum before you charge the system. Mazda no longer sells the expansion valve and poressure switch but I have found aftermaket ones that work and a miata pressure switch is the same.

Don't forget the Schrader valves. I was chasing a SLOW leak, and even with new HVAC Schrader valves it was still leaking there (U/V dye, because the dye don' lie).

I then used Nylog from my local HVAC supplier, and it stopped the leak. And now my master mechanic and I use this on all O-Rings, shaft seals, as it is made from A/C oil.

If you're still with R12 and mineral oil, use Nylog "red", R12, or hydrocarbon-based HVAC refrigerant, like Enviro-Safe (ES) Industrial R12.

Nylog "blue" is for PAG oils, and R134.

IMHO, a conversion from R12 to R134, NEVER cools as well, esp. in hot/humid climates, and I've spent the $$ and labor, to correctly convert. Once I went ES Industrial R12- NO ISSUES.

:-) neil

Schrader valves get a lot of heat being on the exhaust side. Soapy water should be an easy test for them.

Evaporator is easy to pull out so it is worth pulling it to check IMO.

My evap leaked just from some crud build up on the O rings on the expansion valve. I got a new valve from Autozone recently for $20 but parts for the Mana system which I assume is what is on an R1 will be harder to find.

I've been able to do ok with just a cheapie UV kit with the pen light and glasses. The batteries just don't last that long.

134-A conversion done properly is withing a couple degrees of an r-12 system. I have a customer in florida who is very happy with the a/c setup I did for him.

Those couple of degrees might be true at highway speeds, but in my experience it's not the same in stop-n-go traffic with 99% humidity and a heat-index of 115-F.

On an old Mercedes, even with the correct R134a fan assembly, evaporator, expansion valve, receiver/dryer, R134 compresor, R134 pressure switches, etc., it just didn't work as well as the R12 in city traffic.

Same with the 1993 FD, and both were properly flushed, new O-Rings, the FD compressor was extracted and turned upside down to get rid of the old oil (new compressor for the Benz). Dry nitrogen purged and tested for leaks, and then 12+ hrs. on a HVAC vaccuum pump. A graduated HVAC cylinder was used to measure oil and refrigerant, but it still did NOT cool as well as R12. We even double-checked with Temp/Pressure charts for R134 and these cars (my friend is a 20+ year Master ASE Tech).

My neighbor with 1995 FD, which has R134 stock, and has been meticously maintained, could not believe how much cooler my car was than his.

In short, you might be happy/content, but what you don't know, you don't know. Especially until you sit in a FD that feels like an ice-box in 115F heat-index days.

Good reading here:
https://www.rx7club.com/3rd-generati...ht=Enviro+Safe


:-) neil

When I was converting my system I looked at Enviro-Safe and it said not to charge under a vacuum so I was clueless as to how to do a good purge and charge and so just went with the R134a.

Do you just disregard their instructions vac the system anyway?

Yes, hard vacuum, with a REAL HVAC pump.

Read the notes in the link I posted. Very slow charging, and lot's of stabilizing time.

:-) neil

The driers for MANA systems simply cannot be bought, last I checked. Expansion valves are a commodity, off the shelf, universal type of part used on many different cars.