Tired of chasing A/C leaks!

[John B.]

I haven't had working AC in my 535i for more then 2 weeks in several years so with a trip to Tenn. coming up in July I'm thinking about just replacing every 19 year old part of the system. Did the condenser last year so if I buy BMA's rebuilt compressor for $325 I can get out of it for around $1000.

Questions:
1/ Do I really need to replace the hoses? Do they ever fail?

2/ If I've got the dash/heater console ripped apart to replace the evaporator what else should I change while I'm in there? Heater core? Original but no leaks.

3/ To avoid the big expense & just replace the leaking parts has anyone come up with a fool proof way to spot the leaks. I've had the black light search done by several shops but it still leaks.

[ryan roopnarine]

1) is it r12 or has it already been changed?

2) buy one of the black lights from a parts store and see if you can spot the leak yourself. hopefully it is on the evaporator if you are already changing it yourself.

3) they sell r134a 12oz at autozone with dye already in it (no sealant). are you down on charge any? perhaps if you re-dye it by topping it up, you can find the leak in it yourself.

and fyi, they rent a competent vacuum pump and manifold gauge set at autozone if you need them. rent comes out to about 300+ dollars, but you get it back when you are finished. if i were in your situation, i'd check the pressure, top it up as far as you can safely get it, and recheck for leaks yourself with the light.

[Ross]

Yes, the hoses fail. Usually at the ends but sometimes they become porous. If you find oil staining at the fitting ends then suspect a failed crimp. A hydraulic shop should be able to make up new hoses using your existing ends just make sure they know it's for refrigerant so they use the correct material.
O-rings are the biggest leak sources, the condensor too.
I'd suggest using a sniffer rather than trust a visual inspection. The black light method relies on the oil which carries the dye to leak.
The shotgun approach should be effective but you'll be really pissed if you disassemble and find an obvious leak in something minor. I'd rather know what the problem is and correct that.

[Tiger]

As Ryan said... get the vacuum pump first... suck out the system for 30 minutes and then see if there is any leak (by loosing vacuum in the gauge... Be sure the entire system is not under the sun when you do this... the sun temperature will affect the reading.

Then wait 10 minutes to see if you have any loss of vacuum. If not, then I don't see any reason to spend any money. If you are using R134a, then get the one can with sealer and the others without... inject them all in to spec. You are looking for 27 to 30 PSI low side for R134a... I'd fill it to 31 to make sure you have enough refrigerant.

Be absulutely sure you don't inject any air.. you know... from the AC gauge hose... depending on how long they are... just purge the air.

[John B.]

The car was converted to 134A 3-4 years ago & has had dye added at refills a number of times. Each time it was checked with a black light. Last time I had it charged was last summer after replacing the leaking condenser. 4 days later it had lost the charge & was non functional. Considering how much dye has been added with all the recharges the entire car should glow under a black light! If I try the black light myself will the old dye (last summer) still show or have I got to recharge the system & let it leak out again?

I imagine that the "sniffer" is not something I can rent? I'd have to find a shop with one? The shops I've used or spoken to around here seem to only use the black light.

[Tiger]

Sniffer is not really reliable as any gas will set it off.

The dye is green so visually, you can see green goo mess where ever it leaks. the only exception is the compressor... that you may not see it because it is so dirty and the motion of the comrpessor will spray it out.

Another source of leak is the receiver/dryer... also hard to see because it is black, but wiping it with a white paper towel might reveal it under black light.

I suggest you look where hose connects to your evaporator too.

I would also change out the schrader valves since it is a R12 system... valves are cheap. Caps is very important... cap must be on... it is a seal

Now from what you are telling me... after doing the above... I would check it under vacuum again. See if you lose the vacuum in 10 minutes... if you are losing, then I'd say it might be your compressor... with your mileage, I would say it probably is the compressor.

I have bought many compressors off ebay for far cheaper than online auto parts stores.. all work out fine and saved a ton of money. I did a quick search and I couldn't find any... I see BMA is selling a complete kit that upgrades the compressor to a more reliable system... it is a good deal for the kit. You can also find a local AC compressor rebuilder to see how much they charge... Hopefully under $100.

[632 Regal]

When it was converted they were supposed to vacuum all the old oil out and replace it with the correct stuff for 134A (probably did). 134A will leak right through hoses designed for R-12 I believe because the gas molecules are smaller... So.. if the gas can pass through the hoses it doesn't mean that the dye can thus no signs of leakage. Make sure the new hoses are compatable with 134A and that should clear your non AC errors up.

[Bellicose Right Winger]

If they can't find the leak, they may be looking in the wrong places. Is there any evidence of oil from the condensate drain hoses in trans tunnel? This is a good place to sniff with a halogen detector. Consider removing glove box, expansion valve cover and check for dye here. The expansion valve was leaking in my '93 525i. This was VERY surprising as I'd never seen an expansion valve failure cause a leak in 35 years of servicing my AC's. Your car should have a sight glass, it may be hidden by a plastic cover like my '90 535i. It's on the drivers side of the e-box. Follow the small diameter (liquid line) back to the firewall. If there is any dye left in the system, it will show up in the sight glass. It's very difficult to get the dye out after it's in the system. Use the sight glass, or count cans for charging. DO NOT charge to achieve a given low side pressure.

[John B.]

I'll put the car up on the lift tomorrow, remove the front bumper, uncover the evaporator & see what if I can find anything. Hard to believe the original hoses won't hold R134a as many guys seem to have upgraded without changing hoses??

One other question: I'm getting heat out of the foot vents with the temp controls set to cold. Is this simply a flap not closing or would it be related to the heater valve up on the bulkhead? No problems with the dash vents but once in awhile the defrost does the same thing.

[Tiger]

Heater valve...heater will overwhelm the AC anytime.

[John B.]

I ended up replacing everything last week & now have ice cold air just in time for the July heat! A new water control valve & a fix for the broken dash vent cable sheath retainer clip were the only other issues I had to deal with. Lots of crap blocking air flow through the old evaporator so I now have much better air flow into the car. I'll check for leaks again in 4-5 days but I'm hoping this is the end of my A/C issues.

Speaking of A/C I was looking over the set up on our 2002 Frontier yesterday trying to figure out why the A/C sucks so bad in town. Turns out they don't use an aux fan on the condenser which I would have thought was standard on all a/c systems. Is this a typical Japanese set up or did Nissan just cheap out?

[Tiger]

Probably cheaped out... try rigging up something to improve the performance.

[Bill R.]

there is a problem with yours, undercharged or overcharged, nissan air usually is one of the colder ones out there... Nissan uses a pretty heavy duty fan clutch to pull air through the radiator /condensor assy and its usually all thats needed, if you replace the fan clutch use the nissan factory one as the aftermarket hayden/torquo/imperial all seem to be crap compared to the oe.

Back on your original a/c question, R134 systems switched a/c hoses to a type of rubber hoses called barrier hoses which the molecules of r134a couldn't pass through as easily as they can on r12 hose, all replacement hoses now are barrier hoses.
Alot of a/c people theorize that the older r12 hoses were so saturated internally with mineral oil that the leakage rate for r134a wasn't any worse than the original r12 ( 4 ounces per year on most systems is considered normal) I haven't seen that to be the case though but feeding a car a can of 134a each year is a whole lot cheaper than changing all the hoses and seals.




I ended up replacing everything last week & now have ice cold air just in time for the July heat! A new water control valve & a fix for the broken dash vent cable sheath retainer clip were the only other issues I had to deal with. Lots of crap blocking air flow through the old evaporator so I now have much better air flow into the car. I'll check for leaks again in 4-5 days but I'm hoping this is the end of my A/C issues.

Speaking of A/C I was looking over the set up on our 2002 Frontier yesterday trying to figure out why the A/C sucks so bad in town. Turns out they don't use an aux fan on the condenser which I would have thought was standard on all a/c systems. Is this a typical Japanese set up or did Nissan just cheap out?

[John B.]

there is a problem with yours, undercharged or overcharged, nissan air usually is one of the colder ones out there... Nissan uses a pretty heavy duty fan clutch to pull air through the radiator /condensor assy and its usually all thats needed, if you replace the fan clutch use the nissan factory one as the aftermarket hayden/torquo/imperial all seem to be crap compared to the oe..

Still on the original fan clutch at 88k so I guess I need to see how much is in there. The "new" system in my 535i puts out colder air then the Nissan ever has & as I said when you are driving in town it is cool at best unless you switch to recirculate.

[Tiger]

You have to use recirculate majority of the time. Otherwise, you are using outside air to cool the car. Even with recirculation, it still use about 15% outside air.

The only time you don't use recirculate is when it rains... this is the only time or otherwise, inside will fog up.

[John B.]

You have to use recirculate majority of the time. Otherwise, you are using outside air to cool the car. Even with recirculation, it still use about 15% outside air.

The only time you don't use recirculate is when it rains... this is the only time or otherwise, inside will fog up.

The 535i puts out ice cold air without using the recirculate circuit. When I had the blower unit exposed it certainly looked like the fresh air intake flaps were fully closed when the recirculate function was engaged. I never use the recirculate function on any car as I want fresh air coming in.

[DanQ]

1) is it r12 or has it already been changed?

2) buy one of the black lights from a parts store and see if you can spot the leak yourself. hopefully it is on the evaporator if you are already changing it yourself.

3) they sell r134a 12oz at autozone with dye already in it (no sealant). are you down on charge any? perhaps if you re-dye it by topping it up, you can find the leak in it yourself.

and fyi, they rent a competent vacuum pump and manifold gauge set at autozone if you need them. rent comes out to about 300+ dollars, but you get it back when you are finished. if i were in your situation, i'd check the pressure, top it up as far as you can safely get it, and recheck for leaks yourself with the light.

I just found that Autozone in southern New Hampshire no longer rents vacuum pumps.