Automotive Air Conditioning Information Forum (Archives)

wptski on Sat June 15, 2013 9:07 AM

Year: 1990
Make: Buick
Model: Century
Engine Size: 3.3L
Refrigerant Type: R12

The vehicle had about 2psi in the system at the start. Evacuated and system held for a day. At the time I had a can of R12 from another vehicle with just a wisp left in it. Installed it which brought it up from 28/29hg to around 10hg where it stayed for days. Bought four 12oz cans of R12 off Craig's List for $25/can.

I installed one can with car off which brought it to 62psi where it stayed for at least a day. Yesterday I notice it dropped to 50psi at 74F. I did about the same thing on my other R12 vehicle and it varied from 50-60psi with ambient temperature changes. I thought that it would go up as ambient went up and down as it got cooler. This morning it's 60F and it now shows 30psi.

It appears to have a leak but isn't it odd that it would hold vacuum so good, hold pressure for some time and all of a sudden start losing it unless I developed a connection leak? Sadly, I didn't put any sort-of dye in it although the wisp I mentioned was from a can with dye but it's pretty old and wasn't very much anyway. Trying to find a leak using R12 would break my wallet! I'm starting to think R134A conversion again with this vehicle.

Edited: Sat June 15, 2013 at 9:11 AM by wptski

mk378 on Sat June 15, 2013 9:48 AM

Shaft seals and o-rings can do that, holding vacuum but leak under pressure. Use an electronic detector while some of the R-12 still remains. You can static test with 134a without doing a conversion.

94RX-7 on Sat June 15, 2013 10:20 AM

The system holding vacuum basically tells you that the seals are good against no more than atmospheric pressure....~14.7 psi.

wptski on Sat June 15, 2013 10:20 AM

Quote
Originally posted by: mk378
Shaft seals and o-rings can do that, holding vacuum but leak under pressure. Use an electronic detector while some of the R-12 still remains. You can static test with 134a without doing a conversion.
Since I'm a DIY'r, what kind-of money are we talking about with a leak detector? Yeah, I was thinking the same thing about the static R134A testing. Darn, I was going to order some conversion fittings but held back as I "thought" the R12 was going to hold better than this. I could live with a seasonal R12 add but this doesn't look too good!

wptski on Sat June 15, 2013 10:23 AM

Quote
Originally posted by: 94RX-7
The system holding vacuum basically tells you that the seals are good against no more than atmospheric pressure....~14.7 psi.
That's where the use of pressure testing with nitrogen comes in?? Funny that it held for some time and then all of a sudden it starts heading south.


Edited: Sat June 15, 2013 at 10:26 AM by wptski

Dougflas on Sat June 15, 2013 12:11 PM

you should benable to get a used Tek-mate detector on Flea Bay for 75 ish. This is a great detector. Also, place a plastic bag around the compressor (easier and better to remove the belt). After over night sitting with R12 in iot, if it's leaking, you'll know it. And yes, you should have tried to leak test it with R134. Much less expensive. Phantom leaks are usually caused by compressor seals.

wptski on Sat June 15, 2013 12:48 PM

Quote
Originally posted by: Dougflas
you should benable to get a used Tek-mate detector on Flea Bay for 75 ish. This is a great detector. Also, place a plastic bag around the compressor (easier and better to remove the belt). After over night sitting with R12 in iot, if it's leaking, you'll know it. And yes, you should have tried to leak test it with R134. Much less expensive. Phantom leaks are usually caused by compressor seals.
Okay, I see the Tek-Mate uses a sensor elements and a filter of sorts. How do I know if a used one has a working sensor? What are these filters?

Yeah, I'm learning the hard way. There should be a complete step by step for dummies!

mk378 on Sat June 15, 2013 1:31 PM

You test the sensor before each use by deliberately exposing the detector to a (hopefully) tiny amount of refrigerant. Usually removing one of the service caps and finding the refrigerant that has seeped through the shrader valve will work. The filters are little pieces of foam that fit in the end of the wand (the sensor is actually inside the main unit, the wand is just a tube that sucks up samples of air and/or refrigerant and brings it to the sensor). The filters protect against gross contamination with water, oil, dust, etc.

wptski on Sat June 15, 2013 2:44 PM

Quote
Originally posted by: mk378
You test the sensor before each use by deliberately exposing the detector to a (hopefully) tiny amount of refrigerant. Usually removing one of the service caps and finding the refrigerant that has seeped through the shrader valve will work. The filters are little pieces of foam that fit in the end of the wand (the sensor is actually inside the main unit, the wand is just a tube that sucks up samples of air and/or refrigerant and brings it to the sensor). The filters protect against gross contamination with water, oil, dust, etc.
On eBay there were replacement sensors so I assume they don't last forever? I had a old four gas engine analyzer, dug it out to use only to find out that the O2 sensor was dead, wouldn't calibrate and they are obsolete and not available anymore. That's why I'm asking about the sensor and its life span. That every use check is a calibration-like test?



Edited: Sat June 15, 2013 at 3:35 PM by wptski

Dougflas on Sat June 15, 2013 4:34 PM

Those sensors last for years, but yes, eventually they wear out. They will get weak. I have replaced one sensor in 10 years but kept the old ione because it was still good.

wptski on Sat June 15, 2013 4:58 PM

Quote
Originally posted by: Dougflas
Those sensors last for years, but yes, eventually they wear out. They will get weak. I have replaced one sensor in 10 years but kept the old ione because it was still good.
You've had one of these for ten years or some other make/model? AC Kits had a PDF of the manual for it and states 100 hours lifespan. I've asked a seller on eBay about how many hours on the one for sale.



Edited: Sat June 15, 2013 at 5:01 PM by wptski

Dougflas on Sun June 16, 2013 5:41 AM

If you use it for automotive use, it will last much longer. You will learn not to allow it to sense high amounts of freon for extended times on the high sensitivity mode.

wptski on Sun June 16, 2013 10:00 AM

Quote
Originally posted by: Dougflas
If you use it for automotive use, it will last much longer. You will learn not to allow it to sense high amounts of freon for extended times on the high sensitivity mode.
I never looked into if the Tek-Mate is an old model or not but found this relatively new video on YouTube about their new sensor for it:

New Sensor

Dougflas on Sun June 16, 2013 7:42 PM

The new sensor is basically for R410a HVAC uses. The ones that are packaged in the white package will work just fine for MVAC usage.

wptski on Sun June 16, 2013 8:25 PM

Quote
Originally posted by: Dougflas
The new sensor is basically for R410a HVAC uses. The ones that are packaged in the white package will work just fine for MVAC usage.
Well, I'm planning to use R134A for leak detection. The OEM sensor is supposed to be for R134A anyway. The updated sensor is just better??

Dougflas on Mon June 17, 2013 5:24 AM

Quote
Originally posted by: wptski
Quote
Originally posted by: Dougflas
The new sensor is basically for R410a HVAC uses. The ones that are packaged in the white package will work just fine for MVAC usage.

Well, I'm planning to use R134A for leak detection. The OEM sensor is supposed to be for R134A anyway. The updated sensor is just better??

EXactly

wptski on Fri June 21, 2013 2:59 PM

Okay, I got my eBay purchased Tex-Mate today. Tested it on a empty can of R12 that I put some back into just for this test and it seems to work. The problem is the my low side gauge shows 10psi for several days now so the leak to has stopped. I assume that I must remove the R12 and use R134A as the static charge just for leak detection? I thought that it was going to all leak out but seems not.

Edited: Sat June 22, 2013 at 5:34 PM by wptski

Dougflas on Sat June 22, 2013 8:01 PM

Put a can of R134 in it, do the plastic bag trick on the compressor and let us know the results. To use the tek-mate, use the high sesitivity mode. If and when it screams, Hold it there and let it recalibrate. Then continue searching. You'll get the knack real soon.

wptski on Sat June 22, 2013 8:18 PM

Quote
Originally posted by: Dougflas
Put a can of R134 in it, do the plastic bag trick on the compressor and let us know the results. To use the tek-mate, use the high sesitivity mode. If and when it screams, Hold it there and let it recalibrate. Then continue searching. You'll get the knack real soon.

What's the point of letting it recalibrate on a leak? Not exactly what the instructions state

Well I did a bit of a no-no. With the 10psi of R12 in there I added compressed air raise it to about 30psi. The Tex-Mate detected a leak from the front and fitting on the back of the compressor. I removed everything and pumped it down right away.

I plan on using a seal kit but from looking at AC Kits there are two different shaft sizes possible on the HR6HE. I guess I'll have to remove it first and check the shaft before ordering parts. I'm going to replace the accumulator, whatever "O" rings I run in to, use Ester oil because I want to try R134A first. Using Ester oil I can go back to R12 if it performs real bad.

EDIT:
Wonder what Nylog product I could/should use since I may ended up back on R12? Maybe none??



Edited: Sat June 22, 2013 at 8:34 PM by wptski

Dougflas on Sat June 22, 2013 9:55 PM

Quote
Originally posted by: wptski
Quote

Originally posted by: Dougflas

Put a can of R134 in it, do the plastic bag trick on the compressor and let us know the results. To use the tek-mate, use the high sesitivity mode. If and when it screams, Hold it there and let it recalibrate. Then continue searching. You'll get the knack real soon.



What's the point of letting it recalibrate on a leak? Not exactly what the instructions state



Well I did a bit of a no-no. With the 10psi of R12 in there I added compressed air raise it to about 30psi. The Tex-Mate detected a leak from the front and fitting on the back of the compressor. I removed everything and pumped it down right away.



I plan on using a seal kit but from looking at AC Kits there are two different shaft sizes possible on the HR6HE. I guess I'll have to remove it first and check the shaft before ordering parts. I'm going to replace the accumulator, whatever "O" rings I run in to, use Ester oil because I want to try R134A first. Using Ester oil I can go back to R12 if it performs real bad.



EDIT:

Wonder what Nylog product I could/should use since I may ended up back on R12? Maybe none??

The point of letting it recalibrate is to narrow down the exact place of the leak.

WyrTwister on Sun June 23, 2013 6:02 AM

This is a note about pressure remaining in an auto A/C system .

I have a 1991 Chevy Caprice that had belonged to Dad . It has been in storage for 10 - 15 years .

I have been slowly trying to get it back into OK condition ( no trying for restored to perfect condition ) .

It was obvious the oil and R12 had leaked from the compressor shaft seal . Oil had gone everywhere & now , encrusted with dirt .

But it still has a little pressure , inside . Boy , was I surprised !

I have replaced the shaft seal , compressor to line set o-rings , accumulator and added POE oil with yellow / green dye . And R134a .

Still a work in progress . I bought the little UV penlite flashlight & yellow glasses . It looks to be seeping from the o-ring between the shaft side housing & the body of the compressor . I think the other parts I have worked on so far are holding ? Another project , for the future .

God bless
Wyr

Edited: Sun June 23, 2013 at 6:18 AM by WyrTwister

WyrTwister on Sun June 23, 2013 6:30 AM

Quote
Originally posted by: wptski
Quote

Originally posted by: Dougflas

Put a can of R134 in it, do the plastic bag trick on the compressor and let us know the results. To use the tek-mate, use the high sesitivity mode. If and when it screams, Hold it there and let it recalibrate. Then continue searching. You'll get the knack real soon.



What's the point of letting it recalibrate on a leak? Not exactly what the instructions state



Well I did a bit of a no-no. With the 10psi of R12 in there I added compressed air raise it to about 30psi. The Tex-Mate detected a leak from the front and fitting on the back of the compressor. I removed everything and pumped it down right away.



I plan on using a seal kit but from looking at AC Kits there are two different shaft sizes possible on the HR6HE. I guess I'll have to remove it first and check the shaft before ordering parts. I'm going to replace the accumulator, whatever "O" rings I run in to, use Ester oil because I want to try R134A first. Using Ester oil I can go back to R12 if it performs real bad.



EDIT:

Wonder what Nylog product I could/should use since I may ended up back on R12? Maybe none??


I bought some Nylog Blue , but have not tried it yet . Actually bought it for potentially 2 reasons . One , automotive , with R134a . The other is , I am thinking about installing a mini-split HVAC system in the living room .

It seems some / all of these units use flare and flare nut fittings . I read a post that recommended using Nylog Blue on these fittings ?

As far as a seal for your HR6HE compressor , my internet wanderings indicate that the same GM lip seal works on GM R4, DA6 HR6, HR6HE, V5 compressors ? I have used the same seal on my 1991 R4 and 1996 V5 . If you decide to reseal it , holler if I can be of assistance .

As I read it , Nylog Red is used for R12 & mineral oil . So , it sounds like , if you use Nylog , you will need to decide on R12 or R134a ?

God bless
Wyr

wptski on Sun June 23, 2013 9:33 AM

Yeah, I get the same read about the Nylog also. One or the other and you can't change easily.

My '78 Corvette stored for ten years, 13,692 miles on it and worked out good. Drove it for the first time on Thursday and the AC appeared to be working real good.

The '90 Buick also belonged to my parents, 20K on it but was the family backup vehicle so it was driven on/off.

Did you reseal a HR6HE? There seems to be two different shaft sizes.

If one had the proper fittings, etc., you could bench test it for leaks anywhere except the line connections themselves before installing. Your leak is from an "O" ring not provided with the shaft seal kit? Or one you replaced?

I wish you were further ahead on your R134A conversion project. Why did you decided to convert?

WyrTwister on Sun June 23, 2013 11:08 AM

Quote
Originally posted by: wptski
Yeah, I get the same read about the Nylog also. One or the other and you can't change easily.



My '78 Corvette stored for ten years, 13,692 miles on it and worked out good. Drove it for the first time on Thursday and the AC appeared to be working real good.



The '90 Buick also belonged to my parents, 20K on it but was the family backup vehicle so it was driven on/off.



Did you reseal a HR6HE? There seems to be two different shaft sizes.



If one had the proper fittings, etc., you could bench test it for leaks anywhere except the line connections themselves before installing. Your leak is from an "O" ring not provided with the shaft seal kit? Or one you replaced?



I wish you were further ahead on your R134A conversion project. Why did you decided to convert?

Not sure if you are replying to me or the OP ? Oh , well , I will throw in another 2 cents .

The 91 Caprice has about 44,000 original miles . I re-sealed the R4 & replaved the compressor to hose set o-rings . Accumulator . Gassed it up . It still held enough R134a for the clutch to engage & the line from the evaporator to the accumulator , to get cold . At least at idle . Have not started it in a couple of weeks .

I have read some GM compressors had a different shaft size , but have not run into it on the R$ & V5 .

The OP will have to remove the clutch plate any way . Maybe he can use a dial calaper to measure the shaft size . And post the data here for further advice ?

As far as the Caprice in storage . It was at my brother - in - law's place , in the country . The field mice had been having a party in it . Repaired several wires they chewed up .

I am getting " fabric " tuffs in the vents . Would this be insulation ftom the inside of the heater / A/C " box " ? I suspect I will have to take things apart & do a more thorough cleaning ? I suspect the heater core and / or evaporator cor may be at least , partially stopped up with this stuff ?

I think the return line to the accumulator may be getting a lot colder than the air coming out of the vents ?

God bless
Wyr

wptski on Sun June 23, 2013 11:27 AM

Quote
Originally posted by: WyrTwister

Not sure if you are replying to me or the OP ? Oh , well , I will throw in another 2 cents .

The 91 Caprice has about 44,000 original miles . I re-sealed the R4 & replaved the compressor to hose set o-rings . Accumulator . Gassed it up . It still held enough R134a for the clutch to engage & the line from the evaporator to the accumulator , to get cold . At least at idle . Have not started it in a couple of weeks .

I have read some GM compressors had a different shaft size , but have not run into it on the R$ & V5 .

The OP will have to remove the clutch plate any way . Maybe he can use a dial calaper to measure the shaft size . And post the data here for further advice ?

As far as the Caprice in storage . It was at my brother - in - law's place , in the country . The field mice had been having a party in it . Repaired several wires they chewed up .

I am getting " fabric " tuffs in the vents . Would this be insulation ftom the inside of the heater / A/C " box " ? I suspect I will have to take things apart & do a more thorough cleaning ? I suspect the heater core and / or evaporator cor may be at least , partially stopped up with this stuff ?

I think the return line to the accumulator may be getting a lot colder than the air coming out of the vents ?

God bless

Wyr
I am the OP! I reread the shaft seal description again which is confusing the way it's worded. The HR6HE should have have a standard shaft or so it appears on a reread. I will check the shaft anyway before ordering any parts. My Vette was covered but mice chewed the cover up in the cowl area. I didn't see any other damage.

What prompted you to convert to R134A instead of staying on R12?



Edited: Sun June 23, 2013 at 11:29 AM by wptski