No freon, unknown system - what should I do?
05-22-2004, 01:07 PM
#1
Instructor
Thread Starter
Join Date: Jun 2001
Location: Ashburn, VA
Posts: 209
Likes: 0
Received 0 Likes
on
0 Posts
No freon, unknown system - what should I do?
I bought my 928 a little over a year ago. When I bought it, the A/C didn't work (nor did the FI and electricals =). Since I spent last summer repairing it (rather than driving it) I didn't bother with it. With warm weather finally showing up in Pittsburgh, I went ahead and diagnosed the problem. It's just low freon.
Since I don't really know the state of the A/C system, what would be the best approach to take. I'm a little reluctant to just "throw money" at it. I have no idea if it just leaked over time (the car is 20 years old!), or if there's a massive leak somewhere.
What should I do?
I thought of a few different ways to go about it, wanted to get your opinion on my ideas.
- Go ahead and fill it with R12 and a leak detector (maybe just one pound to save money), find the leaks and go ahead and repair the system.
- Go ahead and replace the whole system (maybe with an R134a kit from Griff) and hope it's not the condensor or evaporator that's leaking.
- Evacuate the system, change the fittings, add R134a and leak detector and check for leaks that way.
Can the system be vacuum tested or something similar to check for leaks? (maybe with just a mitivac attached to a fill port?)
Thoughts?
Since I don't really know the state of the A/C system, what would be the best approach to take. I'm a little reluctant to just "throw money" at it. I have no idea if it just leaked over time (the car is 20 years old!), or if there's a massive leak somewhere.
What should I do?
I thought of a few different ways to go about it, wanted to get your opinion on my ideas.
- Go ahead and fill it with R12 and a leak detector (maybe just one pound to save money), find the leaks and go ahead and repair the system.
- Go ahead and replace the whole system (maybe with an R134a kit from Griff) and hope it's not the condensor or evaporator that's leaking.
- Evacuate the system, change the fittings, add R134a and leak detector and check for leaks that way.
Can the system be vacuum tested or something similar to check for leaks? (maybe with just a mitivac attached to a fill port?)
Thoughts?
05-22-2004, 03:51 PM
#2
Rennlist Member
Join Date: Dec 2002
Location: Southern New England
Posts: 1,975
Likes: 0
Received 0 Likes
on
0 Posts
If there is some pressure in there, do a recharge with leak detector.
If there is no pressure, evacuate and see if it holds overnight. If it does, recharge as above. If it doesn't hold the vacuum, pressurize with dry air and check for leaks with "Snoop" or a similar bubbling leak checking fluid.
Stick with R12 if feasible.
If there is no pressure, evacuate and see if it holds overnight. If it does, recharge as above. If it doesn't hold the vacuum, pressurize with dry air and check for leaks with "Snoop" or a similar bubbling leak checking fluid.
Stick with R12 if feasible.
05-22-2004, 10:40 PM
#3
Rennlist Member
Do you know if it's low freon, or no freon? If the system is 'low', but still has enough pressure such that the low pressure switch is not activated, you will be able to confirm the activation of the compressor clutch when the system is turned on. If this is the case, there is ample R-12 left in the system to have a leak test done via a freon 'sniffer'. This could pinpoint a leak, but is more likely to show no leak: the latter would the better outcome, for a R-12 recharge could cure the system. Schreader valves and dry seals can be responsible for very slow leakages that are difficult to detect ( eg., look for a film of oil inside the schreader valve caps = slow leak).
05-22-2004, 11:04 PM
#4
Addict
Rennlist Member
Rennlist Member
I'm kind of going backwards, but you'll see why.
If there is no pressure, evacuate the system and check for leaks. Next, fill the system with nitrogen (clean inert gas). Some leaks don’t show up under vacuum, it takes pressure. Nitrogen is much less expensive than Freon. If the system holds pressure, then charge with Freon and a dye.
Be aware that even if the hoses hold for a few days, they can burst at a later date and all that expensive Freon goes into the air. If you have the funds, before charging and testing the system remove the hoses, take them to a shop that replaces the rubber and have the new double barrier. It is also suggested to replace the receiver/dryer.
Even better, in addition to replacing all the rubber hoses, replace all the O-rings (sealing rings) in the system before charging.
You'll need to decide if you stay with Freon or go to R134a due to the type of sealing rings. In your area, R134a may be OK. I've heard that it is less efficient in a system designed for Freon, so it is your choice.
If you go with R134a and have replace all the rubber hose lines and O-rings, you'll need to remove the compressor and drain out the oil and replace it with oil that is compatible with R134a.
A/C work is rather specialized and mistakes can cost a lot of money. So, I suggest that a qualified shop do the work, you'll end up spending less in the long run.
If there is no pressure, evacuate the system and check for leaks. Next, fill the system with nitrogen (clean inert gas). Some leaks don’t show up under vacuum, it takes pressure. Nitrogen is much less expensive than Freon. If the system holds pressure, then charge with Freon and a dye.
Be aware that even if the hoses hold for a few days, they can burst at a later date and all that expensive Freon goes into the air. If you have the funds, before charging and testing the system remove the hoses, take them to a shop that replaces the rubber and have the new double barrier. It is also suggested to replace the receiver/dryer.
Even better, in addition to replacing all the rubber hoses, replace all the O-rings (sealing rings) in the system before charging.
You'll need to decide if you stay with Freon or go to R134a due to the type of sealing rings. In your area, R134a may be OK. I've heard that it is less efficient in a system designed for Freon, so it is your choice.
If you go with R134a and have replace all the rubber hose lines and O-rings, you'll need to remove the compressor and drain out the oil and replace it with oil that is compatible with R134a.
A/C work is rather specialized and mistakes can cost a lot of money. So, I suggest that a qualified shop do the work, you'll end up spending less in the long run.
05-23-2004, 03:03 PM
#5
Drifting
Ben,
Rich has some good advice with avoiding mistakes. Getting a couple of estimates or working with someone you can trust might save you some money now or later.
Rich has some good advice with avoiding mistakes. Getting a couple of estimates or working with someone you can trust might save you some money now or later.
05-23-2004, 03:14 PM
#6
Instructor
Thread Starter
Join Date: Jun 2001
Location: Ashburn, VA
Posts: 209
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for the tips guys.
I had to jumper the low freon switch in order to get the compressor clutch to energize, so there's very little, if any, freon in the system. The compressor does not make any horrid noises, so there's likely still oil in the compressor.
Sounds like the best approach is to have an A/C shop rebuild the hoses, replace all the o-rings and the receiver/dryer before filling with R12. Doesn't sound too expensive (especially if there's an OEM r/d available)
I had to jumper the low freon switch in order to get the compressor clutch to energize, so there's very little, if any, freon in the system. The compressor does not make any horrid noises, so there's likely still oil in the compressor.
Sounds like the best approach is to have an A/C shop rebuild the hoses, replace all the o-rings and the receiver/dryer before filling with R12. Doesn't sound too expensive (especially if there's an OEM r/d available)
