OK, Let's renew our AC system
07-20-2013, 08:18 PM
#46
Administrator
Thread Starter
How much are you guys paying for your R-134a?
Not that I would use it except for a job,
I checked and a 30# cylinder is $114.00 at my local HVAC supply house and has a standard Acme thread post valve.
Removing my serpentine belt is an easy task, don't know why you guys are having so much difficulty, my old tensioner had the 3/8" square drive so I used a short breaker bar and a section of EMT conduit to extend the handle,
When I replaced the tensioner the new one now has a 1/2" square drive, I found 1/2" breaker was too bulky to get into the space between the shroud yet the 3/8" had no problem, so here is what I did.
I cut me a section of 1/2" OD x3/8" ID square tubing to fit into the new tensioner, now the old 3/8" breaker fits inside the square adapter and unloads the tensioner with ease.
What is this breaker bar I speak of, you probably have one and didn't know what is was called.
The head if most standard ratchet wrenches are too bulky to get in next to the shroud.
Here take a look,
http://m.homedepot.com/p/Husky-3-8-i...BB10/202923416
I can remove my serpentine belt in less then 2 minuets.
When reinstalling the belt, be aware that it will try and hang on the lower timing case bolt, you need to twist the belt slightly to slip it onto the crank pulley.
This is what has worked for me.
I keep this small adapter in my ash tray for safe keeping.
Jim
Not that I would use it except for a job,
I checked and a 30# cylinder is $114.00 at my local HVAC supply house and has a standard Acme thread post valve.
Removing my serpentine belt is an easy task, don't know why you guys are having so much difficulty, my old tensioner had the 3/8" square drive so I used a short breaker bar and a section of EMT conduit to extend the handle,
When I replaced the tensioner the new one now has a 1/2" square drive, I found 1/2" breaker was too bulky to get into the space between the shroud yet the 3/8" had no problem, so here is what I did.
I cut me a section of 1/2" OD x3/8" ID square tubing to fit into the new tensioner, now the old 3/8" breaker fits inside the square adapter and unloads the tensioner with ease.
What is this breaker bar I speak of, you probably have one and didn't know what is was called.
The head if most standard ratchet wrenches are too bulky to get in next to the shroud.
Here take a look,
http://m.homedepot.com/p/Husky-3-8-i...BB10/202923416
I can remove my serpentine belt in less then 2 minuets.
When reinstalling the belt, be aware that it will try and hang on the lower timing case bolt, you need to twist the belt slightly to slip it onto the crank pulley.
This is what has worked for me.
I keep this small adapter in my ash tray for safe keeping.
Jim
07-21-2013, 10:42 PM
#47
Administrator
Thread Starter
The low pressure cutout switch is available at rockauto Part# PCS127 here:
http://www.rockauto.com/catalog/x,ca...parttype,11748
The seal kit also at rockauto FOUR SEASONS Part # 26700 and GPD Part # 1321234 both here:
http://www.rockauto.com/catalog/x,ca...parttype,13290
This kit does not include the o-rings for the hose connections at the manifolds.
The expansion valve listed at rockauto is not correct for 89-91.5 trucks, the correct one is on ebay, just search the part# 3411283
The correct part# for inter-cooled trucks is: GPD Part # 3411284 & FOUR SEASONS Part # 38849
found here: https://www.rockauto.com/catalog/x,c...,parttype,6788
Mark
http://www.rockauto.com/catalog/x,ca...parttype,11748
The seal kit also at rockauto FOUR SEASONS Part # 26700 and GPD Part # 1321234 both here:
http://www.rockauto.com/catalog/x,ca...parttype,13290
This kit does not include the o-rings for the hose connections at the manifolds.
The expansion valve listed at rockauto is not correct for 89-91.5 trucks, the correct one is on ebay, just search the part# 3411283
The correct part# for inter-cooled trucks is: GPD Part # 3411284 & FOUR SEASONS Part # 38849
found here: https://www.rockauto.com/catalog/x,c...,parttype,6788
Mark
07-28-2013, 10:08 PM
#48
Administrator
Thread Starter
How much are you guys paying for your R-134a?
Not that I would use it except for a job,
I checked and a 30# cylinder is $114.00 at my local HVAC supply house and has a standard Acme thread post valve.
Removing my serpentine belt is an easy task, don't know why you guys are having so much difficulty, my old tensioner had the 3/8" square drive so I used a short breaker bar and a section of EMT conduit to extend the handle,
When I replaced the tensioner the new one now has a 1/2" square drive, I found 1/2" breaker was too bulky to get into the space between the shroud yet the 3/8" had no problem, so here is what I did.
I cut me a section of 1/2" OD x3/8" ID square tubing to fit into the new tensioner, now the old 3/8" breaker fits inside the square adapter and unloads the tensioner with ease.
What is this breaker bar I speak of, you probably have one and didn't know what is was called.
The head if most standard ratchet wrenches are too bulky to get in next to the shroud.
Here take a look,
http://m.homedepot.com/p/Husky-3-8-i...BB10/202923416
I can remove my serpentine belt in less then 2 minuets.
When reinstalling the belt, be aware that it will try and hang on the lower timing case bolt, you need to twist the belt slightly to slip it onto the crank pulley.
This is what has worked for me.
I keep this small adapter in my ash tray for safe keeping.
Jim
Not that I would use it except for a job,
I checked and a 30# cylinder is $114.00 at my local HVAC supply house and has a standard Acme thread post valve.
Removing my serpentine belt is an easy task, don't know why you guys are having so much difficulty, my old tensioner had the 3/8" square drive so I used a short breaker bar and a section of EMT conduit to extend the handle,
When I replaced the tensioner the new one now has a 1/2" square drive, I found 1/2" breaker was too bulky to get into the space between the shroud yet the 3/8" had no problem, so here is what I did.
I cut me a section of 1/2" OD x3/8" ID square tubing to fit into the new tensioner, now the old 3/8" breaker fits inside the square adapter and unloads the tensioner with ease.
What is this breaker bar I speak of, you probably have one and didn't know what is was called.
The head if most standard ratchet wrenches are too bulky to get in next to the shroud.
Here take a look,
http://m.homedepot.com/p/Husky-3-8-i...BB10/202923416
I can remove my serpentine belt in less then 2 minuets.
When reinstalling the belt, be aware that it will try and hang on the lower timing case bolt, you need to twist the belt slightly to slip it onto the crank pulley.
This is what has worked for me.
I keep this small adapter in my ash tray for safe keeping.
Jim
08-06-2013, 01:37 PM
#49
Administrator
Thread Starter
High pressure relief valve
Well, I began having a freon leak from my new ac system. I came out 1 morning and there was some compressor oil on the ground. Well I removed the compressor and it turned out that the high pressure relief valve, which is on the high side manifold, was partially stuck open. The worst part is that it would hold a vacuum, but then leak when under pressure. I searched for a couple of hours on the web and came up with nothing, so I went down to the ac store and they had them in stock. It is 4seasons part# 35745. It has an o-ring and that should be changed when the system is renewed. For 20 bucks, it is probably worth replacing the over pressure valve also...Mark
08-29-2013, 03:54 PM
#50
Administrator
Thread Starter
I have done some research about how to charge a system with R134-A. I was pretty lucky to get the charge pretty close to right the first time I charged the system. As many people have said, 134a operates at higher pressure than R-12 and as a result it is a different animal. I have found out that the rule of thumb that the experts use for the conversion is:
1. The best way to determine the amount of 134a that has been installed is to do it by weight. The sight glass means NOTHING with 134a. If you take it to a clear condition, IT IS WAYYYYY OVER CHARGED.
2. To calculate the weight necessary, take 85 percent of the amount of r12 required. If it is 2lbs of r12 (just an example, I don't remember how much r12 was in the Dodge system), it will be 1.7lbs of r134a. You then take 85% of that, 1.5lbs, that is how much you put in. Run the rpms up to approximately 2000 as you are putting in the freon and keep an eye on the gauge, especially the high side. There are charts that will give you pressures that you should see at different atmospheric conditions. Here is a 134a pressure calculator. You then use the temperature of the air it is putting out to top it off. The professionals use laser or other digital thermometers that are very accurate. After you have the 1.5lbs (from the example) installed, you SLOWLY FEED IN THE FREON as you watch the temp. As soon as the temperature GOES UP 1 DEGREE, STOP, it is fully charged. The pros that have the automatic machines will then actually remove some freon until it goes down 1 degree, but I can live with 1 degree. Amazon has some relatively inexpensive freon scales.
3. The real problem with recharging a system is how much oil to put in. When the system is new and relatively dry, it is easy. When a charge has been lost, as in my case, it is very hard to know how much oil was lost. The BEST way is to disassemble the system, flush and refill it with the required amount of oil . If you put in too much oil, it will affect system performance, if not enough, well you know what will happen in this case. So I estimated and added a 2 ounce oil charge, but the truth is that I have no idea how much oil is in the system now.
4. Forget the sight glass, it will get you in trouble.
Hope this is as clear as mud...Mark
1. The best way to determine the amount of 134a that has been installed is to do it by weight. The sight glass means NOTHING with 134a. If you take it to a clear condition, IT IS WAYYYYY OVER CHARGED.
2. To calculate the weight necessary, take 85 percent of the amount of r12 required. If it is 2lbs of r12 (just an example, I don't remember how much r12 was in the Dodge system), it will be 1.7lbs of r134a. You then take 85% of that, 1.5lbs, that is how much you put in. Run the rpms up to approximately 2000 as you are putting in the freon and keep an eye on the gauge, especially the high side. There are charts that will give you pressures that you should see at different atmospheric conditions. Here is a 134a pressure calculator. You then use the temperature of the air it is putting out to top it off. The professionals use laser or other digital thermometers that are very accurate. After you have the 1.5lbs (from the example) installed, you SLOWLY FEED IN THE FREON as you watch the temp. As soon as the temperature GOES UP 1 DEGREE, STOP, it is fully charged. The pros that have the automatic machines will then actually remove some freon until it goes down 1 degree, but I can live with 1 degree. Amazon has some relatively inexpensive freon scales.
3. The real problem with recharging a system is how much oil to put in. When the system is new and relatively dry, it is easy. When a charge has been lost, as in my case, it is very hard to know how much oil was lost. The BEST way is to disassemble the system, flush and refill it with the required amount of oil . If you put in too much oil, it will affect system performance, if not enough, well you know what will happen in this case. So I estimated and added a 2 ounce oil charge, but the truth is that I have no idea how much oil is in the system now.
4. Forget the sight glass, it will get you in trouble.
Hope this is as clear as mud...Mark
08-30-2013, 08:31 AM
#52
Administrator
Thread Starter
On a hot, dry day, IIRC, It was about 180 on the high side and around 40 on the low side. I am not sure of the exact numbers. The problem is that when I did my last charge my hvac plenum was full of pine needles, see page 4 here. AS Jim Lane said in a thread, R134a really likes air flow across the coils. I haven't put the gauges on since I cleaned out the box. My system drops around 5 degrees from idle to running down the freeway. Because of this, they talk about putting a high velocity fan in front of the condenser when checking or charging a system and running up the rpms to 2000. The days of simple R12 charging are over, the site glass is useless and 134a requires more thought. The charts will give you an idea of what the numbers should be at different atmospheric conditions...Mark
09-05-2013, 05:42 PM
#53
Administrator
Thread Starter
09-06-2013, 04:30 PM
#54
Administrator
Thread Starter
While I was reading the owners manual for a different thread, I found that the original owner of the truck had put the original a/c label inside it. It must have come off and he stuck it in there. Any hoo, it says that the diesel R12 system has 1.16 kilos or 41 ounces of R12, so 85% of 1.16 kilos (41 ounces) is .986 kilos (34.85 ounces), which would be the maximum amount of R134A to put in. 85% of that is: .8381 kilos (29.662 ounces), this is what you put in first...Mark
06-09-2014, 06:24 AM
#55
Registered User
Mark: Wouldn't happen to have the part number for the metal gasket that goes into the coil (front of the intercooler?). Wonder what a good price would be to have a shop flush/ put new stuff in. That way they can check on leaks and what not.
06-09-2014, 08:58 AM
#56
Administrator
Thread Starter
09-07-2014, 08:49 PM
#57
Administrator
Thread Starter
New info
Well, I began having a freon leak from my new ac system. I came out 1 morning and there was some compressor oil on the ground. Well I removed the compressor and it turned out that the high pressure relief valve, which is on the high side manifold, was partially stuck open. The worst part is that it would hold a vacuum, but then leak when under pressure. I searched for a couple of hours on the web and came up with nothing, so I went down to the ac store and they had them in stock. It is 4seasons part# 35745. It has an o-ring and that should be changed when the system is renewed. For 20 bucks, it is probably worth replacing the over pressure valve also...Mark
. I did find a reference to a cut out switch conversion that eliminates the pop off valve. I am going to check on this and report back, carry on 
...Mark
01-28-2016, 03:10 PM
#58
Administrator
Thread Starter
All the links are good, except for the low pressure cutout switch. It is now located here: RockAuto Parts Catalog . All of the pics are good. One other thing that I want to point out is that some of the info contained here only appies to 4 wheel drive trucks, specifically being able to access the top of the compressor without pulling it. Thanks to Brucem for pointing this out...Mark
01-30-2016, 01:43 PM
#59
Registered User
Wow, this is old! Ha.
Nice job, Mark and thanks for the part number for the expansion valve. I ran into that same issue years back when I refreshed my system. I ended up just cleaning the existing one thoroughly.
Nice job, Mark and thanks for the part number for the expansion valve. I ran into that same issue years back when I refreshed my system. I ended up just cleaning the existing one thoroughly.
01-30-2016, 03:18 PM
#60
Administrator
Mark,
Did you ever find a replacement high pressure relief valve for your compressor for R-134?
I converted mine to a Sanden SD709, this compressor is for R-134 and the relief valve is on the back of the head, it is a short stubby valve.
At one time I was thinking of blocking off the relief valve and simply installing an adjustable Penn switch to control the compressor.
BTW the plug that comes on a new expansion valve is the identical thread & o-ring to block off the high pressure relief valve.
I was told a relief valve for R-12 will pop around 500-550 psi.
Jim
Did you ever find a replacement high pressure relief valve for your compressor for R-134?
I converted mine to a Sanden SD709, this compressor is for R-134 and the relief valve is on the back of the head, it is a short stubby valve.
At one time I was thinking of blocking off the relief valve and simply installing an adjustable Penn switch to control the compressor.
BTW the plug that comes on a new expansion valve is the identical thread & o-ring to block off the high pressure relief valve.
I was told a relief valve for R-12 will pop around 500-550 psi.
Jim