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Old 06-24-2012, 12:24 PM   #21
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Originally Posted by 94mx5red View Post
I think the low side is supposed to hold low rather than rising. Mechanic said the low side rises and the compressor shuts down. Probably a sensor tells it to.

I have to read through everything I already forgot from my research this week. At a minimum, I know I am low on freon.

i just had a bottle on my altima. sat at nearly 200psi when the compressor wasn't running, then would drop to around 55psi as the compressor kicked on.
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Old 06-24-2012, 12:34 PM   #22
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You need more 134a



Last week I had to evac/leak test/and charge a car. I sweat more then it did, but it was 95 degrees out, original dict temps were 120+, but I got them down to sub 40 degrees. Not sure what the low side numbers were because I don't care much about them as long as they are within range, but the high side was getting up into the 250-275 range. Make sure you have your fans on, otherwise you'll get high pressure readings but crappy duct temps.
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Old 06-24-2012, 01:40 PM   #23
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Originally Posted by 94mx5red View Post
http://blog.choppedoctopus.com/2011/...ing-my-ac.html

Looking promising.

Thinking about picking up a used compressor and sealed evaporator unit that hopefully has a good expansion valve, and a new drier.

Also considering cleaning my existing evaporator and putting a new expansion valve on it.

Anyone with a evaporator unit pulled they want to sell cheap?
Where is this guy getting parts so cheap? I'm blowing 40-50*f AC air, do I need to service my car? Of course I'd love to have it colder. At 104*f today, the AC struggles to keep me comfortable. Also, how do I know which o-rings to get?

My GF's Cherokee has been to the shop in Houston 3-times and they keep replacing ----, but refrigerant keeps leeking. I have to pull the dash in this thing, I know it.
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Old 06-24-2012, 03:07 PM   #24
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Evap/condenser/coil cleaner is $5 a can at home depot. Every AC evaporator I've pulled from NA Miatas has been packed/caked with crap. There's really nothing stopping the junk from getting in there like a filter on more modern cars. New Miata expansion valve is $20.

If you're running 134 in an r12 system, it just won't work as well using r134 components due to the differences in the refrigerants. Mine is acceptable with a 134 compressor and r12 condenser in Atlanta, so I'm not surprised your's struggling in TX. You can get a 134 condenser and compressor for an NA. IMO the condenser would make the biggest difference.

When I service an AC system, I pull a strong vacuum on it and let it sit over night. If it reads the same, then I finish the job. They should be checking for leaks before charging it.
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Old 06-24-2012, 03:14 PM   #25
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Where can I get a can-punch locally, on a sunday?

How well does that cleaner work? I'm trying to avoid buying the $180 vacuum pump.
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Old 06-24-2012, 03:53 PM   #26
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This is for the exchanger exterior- it between the fins of any coil and IMO does a phenomenal job. It works well on any heat exchanger- but the condenser is the first thing in line on an AC Miata in the mouth. Checking the condenser fins is the easiest thing check and the cheapest to fix/clean. My condenser was out (I built my last miata AC sys from parts) but you'll want to slide something between your condenser and the rad so when you spray it, the **** doesn't just blow into the rad fins.

Look into the evap/AC air intake for garbage. If you're more ambitious you can pull the glove box and intake tube, then stick your had in there to check for trash/gunk/blockage. In theory you could spray the cleaner in through the intake connection point, and onto the evaporator fins. Then spray it with a stream of water and all of it would drain out the evap drain hole... until it got clogged. Then you'd be unclogging that from the drop hose. IMO there's no point in replacing parts until you're sure those two things are as good as they get.



You want an aerosol cleaner in a can- not the thing with the pump/sprayer head, hose and connected jug.
This: http://www.homedepot.com/h_d1/N-5yc1...&storeId=10051
or this
http://www.homedepot.com/h_d1/N-5yc1...&storeId=10051
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Old 06-24-2012, 04:28 PM   #27
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Just fixed the ac on the wife's jetta. Miata pushed to the end of the line for today.

76*f and rainy. Getting the outer edges of the tropical storm Debbie. No good storms yet, but there is still a chance.

Jetta was at 30 low 100 high, compressor on- warm air. Added a can with a stop-leak and now at 30 low 150 high, blowing cold.
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Old 06-25-2012, 07:43 PM   #28
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Going to have to pick up a new low side feed tube too. Walked past the car a while after finishing, and I heard it leaking from the port. It's similar to a tire valve. Messed around with the little thing in the hole and stopped the leak.
------- low side valve slow leaked everything out.

24oz of freon - not even getting cool. 85*f and not nearly enough added.

Suggestions are needed now.
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Old 06-25-2012, 08:11 PM   #29
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Stupid leak:



Down to 25psi static pressure before starting today.


Ended up around 150 high. Very surprised at the low side.




I cannot seem to find it now, but the low side valve is a short section of pipe, maybe $20.

Now I am looking at draining it and throwing parts at it. What do you think about my compressor? Pulls good vacuum...leaky somewhere near it. Anyplace on it where they leak other than the entry and exit points?
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Old 06-26-2012, 01:37 AM   #30
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Quote:
Originally Posted by hustler View Post
Where is this guy getting parts so cheap? I'm blowing 40-50*f AC air, do I need to service my car? Of course I'd love to have it colder. At 104*f today, the AC struggles to keep me comfortable. Also, how do I know which o-rings to get?

My GF's Cherokee has been to the shop in Houston 3-times and they keep replacing ----, but refrigerant keeps leeking. I have to pull the dash in this thing, I know it.
40 degree duct temps in 104 outside temps is pretty damn good.

You probably will end up pulling the dash... XJ's eat evap's. Lucky for you, its not that bad.
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Old 06-26-2012, 10:37 AM   #31
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Originally Posted by 94mx5red View Post
------- low side valve slow leaked everything out.
24oz of freon - not even getting cool.
The schrader valve is replaceable- if that is what's causing the leak at the fill port. fwiw- you should use less r134 than the spec'd amount of r12 for an r12 system. I believe it's 80% - but more refrigerant does not mean colder. Do you have a vacuum pump? I'm assuming you do since you've filled the system. I would pull a vacuum after the repair and make sure it holds- overnight is what I do, but at least an hour to make sure it's not leaking.
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Old 06-27-2012, 08:42 AM   #32
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Originally Posted by m2cupcar View Post
The schrader valve is replaceable- if that is what's causing the leak at the fill port. fwiw- you should use less r134 than the spec'd amount of r12 for an r12 system. I believe it's 80% - but more refrigerant does not mean colder. Do you have a vacuum pump? I'm assuming you do since you've filled the system. I would pull a vacuum after the repair and make sure it holds- overnight is what I do, but at least an hour to make sure it's not leaking.
I would never have guessed it is called a schrader valve or replaceable. Quick search last night, there are tools that can replace without discharging the system. Very neat. need to read more.

This is for my 1999, was it an r12 originally? I have not found the exact fill amount, and am using the chart on post #22 as a guide.

Do not have a vacuum pump (shopping around). There was still around 25psi Monday, and the cans flowed in just fine. My noob logic was: if there is pressure in the system then there must be no air...

Thought I had too low of a fill, but yesterday, ac worked great. Maybe 75% of how I think it should be.

Will be picking up cans of the coil cleaner. Auto parts store did not have any.
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Old 06-27-2012, 09:18 AM   #33
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Forgot it was a 99- so no never r12, 134 always. Noob logic is correct mostly- if there's more pressure in than out, then the out can't get in. Sounds like you're safe to me. I have had similar experiences with the last system I did. Vent temp dropped 15f after driving it around compared to sitting in the garage idling after charge. Schrader valve will ultimately (eventually) be cheaper than refrigerant.
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Old 06-28-2012, 03:05 AM   #34
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The thermoswitch on 99+ is set to 38* so 40 vent is about it... The older ones can be fooled colder by spacing the expansion valve temp sensor off using a piece of tape between it and the pipe. Iirc it's been like 7 years since I looked at a NA.
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Old 06-28-2012, 05:55 PM   #35
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Where can I get a can-punch locally, on a sunday?

How well does that cleaner work? I'm trying to avoid buying the $180 vacuum pump.
You can pick up this vacuum pump from HF for cheap. As long as you have a decent air compressor, this thing will work.

Vacuum Pump - AC Vacuum Pump w/ R134A & R12 Connectors
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Old 06-28-2012, 09:25 PM   #36
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^looks awesome and much less than a standalone pump.


Quote:
Originally Posted by m2cupcar View Post
Schrader valve will ultimately (eventually) be cheaper than refrigerant.
Understatement of the century! New valve and cap = personal best of least money spent at an autoparts store.

I learned the cap is an integral part of the schrader valve, containing an o-ring. Mine was missing.







This valve replacer arrives tomorrow. Supposed to be able to replace the valve without emptying freon.

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