Not blowing cold air

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DentalDart

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Ok so my compressor works (I think), my air blows just not cold (besides today because it's cold outside) and my clutch on my compressor engages.

Would this mean I just need to charge the system? I tried charging it before, doing the whole page oil then filling with R134A but it didnt work.

Any ideas? I'd love to have A/C this summer
 
Usually that is what it means. Am concerned that you may have a leak. I think better "O" rings are needed with R134. A dye is put in the system to find leaks.
 
Usually that is what it means. Am concerned that you may have a leak. I think better "O" rings are needed with R134. A dye is put in the system to find leaks.

So maybe I should look for some R12 or dye that would help determine if I have a leak.
 
There are two ways to do this: To do it correctly, need to draw the system down to evacuate it and hold a vacume for awhile, if it wont hold a vacume, the system is not tight and has a leak. You will need the guages and a vacume pump for this.
Assuming theres no leaks, (if you cant hold a vacume, partially charge system with a dye) If the system is tight, add the proper amount of refrigerant without releasing the vacume. Too much freon will also cause a warm air condition. The compressor will cycle on and off intermittently when operating normally.
The car has Low and Hi psi sides. The larger diameter lines on the car is Low, the smaller lines are high side psi. (The pressure drop makes the freon cold at the Thermal expansion valve at the firewall, you can feel the cold pipe when its working properly). Always add freon to the Low side.
Note: The guages have 3 hoses, Red for Hi, Blue for Low and the third hose (can be any color) is for accessory, like a vacuum pump or adding freon. Each guage has a valve, opening the valve will allow the 3rd hose direct feed (or draw) from the accessory hose. All freon is as added to the Low side guage. This guage is a compound guage and reads inches of mercury (hg) past 0 psi, (negative psi or vacume).
Its a doable project, if you have the right tools.
Now that you know the theory:
If you dont have the tools, check for leaks with a dye and remember, the evaporator (like a heater core) can be leaking inside the dash). If you add refrigerant w/o a sealed vacume tight system, it may work, but never as cold as it is capable of blowing.
Good luck.
 
Ok so my compressor works (I think), my air blows just not cold (besides today because it's cold outside) and my clutch on my compressor engages.
Would this mean I just need to charge the system? I tried charging it before, doing the whole page oil then filling with R134A but it didnt work.
Any ideas? I'd love to have A/C this summer

Hello DentalDart,
What are we working on? (year, make, stock or aftermarket AC)
Please read and understand what Joey4speed added in his post,
Then can you do the following?
Can you provide a pix of the under hood?
First step is to put a set of gauges on the High and Low side.
What are the reading with the engine off? Note: take readings after the engine / compressor has been off for 10 minutes. If there zero stop and let us know.
Both high and low should be approximately the same (equalized).
Second step. With gauges still connected to the High and Low side run the engine and put the system into max (full cool) and confirm the compressor crank shaft (not only clutch) is turning (nut in center of clutch).
What is the reading on the gauges at this point? The high side should be over 100 Psi and the low should be under 50. NOTE: The readings will differ with ambient temp and inside car temp. Psi readings I am given are for example only but should be a starting point.
Third Step.
Questions,
With engine running and the system off (all slide control's and fan off on dashboard) when selecting heat Or ac do you here the damper doors in the heater / ac under dash box moving? (vacuum sounds).
With the system in Max / Full cool is the fan running in high speed?
With the compressor running does it cycle on and off? if so how often?
If so what are the gauges doing at this time?
If the high side is above 100 Psi and the low is under 50 psi with system running carefully (use inferred gun if possible) check the following.
Temp of inlet hose to compressor?
Temp of outlet hose to compressor?
Temp of inlet hose to condenser?
Temp of outlet hose to condenser?
Temp of inlet hose to filter dryer?
Temp of outlet hose to filter dryer?
Temp of inlet hose to evaporator?
Temp of outlet hose to evaporator ?
Temp of inlet hose to expansion valve?
Temp of outlet hose to expansion valve?
Note: The temp readings you are taking and supplying don't need to be scientific just as best as you can get them.
Perform the above tests and let us know the results so we can further help you.
Happy Mopar :)
Arron
Edit = clarification of description.
 
Last edited:
My knowledge is limited but my understanding is that R12 is illegal and not available. You will be dealing with R134. Here is a photo of the proper gauge, a two gang is more common. Has been too long from the trade to offer much advise. The help so-far has been good.
100_2625.JPG
 
There are two ways to do this: To do it correctly, need to draw the system down to evacuate it and hold a vacume for awhile, if it wont hold a vacume, the system is not tight and has a leak. You will need the guages and a vacume pump for this.
Assuming theres no leaks, (if you cant hold a vacume, partially charge system with a dye) If the system is tight, add the proper amount of refrigerant without releasing the vacume. Too much freon will also cause a warm air condition. The compressor will cycle on and off intermittently when operating normally.
The car has Low and Hi psi sides. The larger diameter lines on the car is Low, the smaller lines are high side psi. (The pressure drop makes the freon cold at the Thermal expansion valve at the firewall, you can feel the cold pipe when its working properly). Always add freon to the Low side.
Note: The guages have 3 hoses, Red for Hi, Blue for Low and the third hose (can be any color) is for accessory, like a vacuum pump or adding freon. Each guage has a valve, opening the valve will allow the 3rd hose direct feed (or draw) from the accessory hose. All freon is as added to the Low side guage. This guage is a compound guage and reads inches of mercury (hg) past 0 psi, (negative psi or vacume).
Its a doable project, if you have the right tools.
Now that you know the theory:
If you dont have the tools, check for leaks with a dye and remember, the evaporator (like a heater core) can be leaking inside the dash). If you add refrigerant w/o a sealed vacume tight system, it may work, but never as cold as it is capable of blowing.
Good luck.

Thanks for this, I dont have the correct guages and a/c tools to do it the first way mentioned. Maybe I can find some on in the local fs ads though.
 
Thanks for this, I dont have the correct guages and a/c tools to do it the first way mentioned. Maybe I can find some on in the local fs ads though.
Or take it to a mechanic that has the correct tools. Is it a R12 system converted to R134a? That can cause some performance issues right there.
 
69 dart with 68 340 engine. Stock ac setup.

Heres pictures and video. Should I replace the dryer since I tried putting R134A in it?



20200321_101729.jpg


20200321_101742.jpg


20200321_101751.jpg
 
Usually that is what it means. Am concerned that you may have a leak. I think better "O" rings are needed with R134. A dye is put in the system to find leaks.
That and make sure the heater door is closing and not blending hot air into the mix.
 
This is the more expensive option:poke:.... but most likely the smartest option.
Hello DentalDart,
See if at lease you can get us the High and Low Psi when not running and when running. Some auto stores loan gauges or check with a friend. This will at least help us get you in some direction before you replace anything or take it to someone.
When the compressor is running is the high and low sides at least warm or cool to the touch?
Let us know,
Happy Mopar:)
Arron
 
R12 is not illegal and it is available. You just have to know where to look. I just bought 4 cans at our Lincoln Swap Meet a couple weeks ago for 10.00 a can. I have never seen an old R12 Mopar system that has been converted to R134 work worth a damn! Ask around, there is always some around, garage sales, always swap meets or someone like me that has about 75 lbs.
 
doing the whole page oil
Should I replace the dryer since I tried putting R134A in it?

A/C service is something that requires a high degree of precision. You drained, flushed the compressor of all mineral and added polyalkylene glycol a.k.a. PAG with out replacing the dryer? A recipe for failure for sure. If you left any mineral oil in the system it's worse. Poly Ester oil is compatible with R12 and R134a and is much better suited to vintage retrofits. It is readily available in most auto part stores.

https://www.autozone.com/a-c-chargi...er-refrigerant-oil-with-ice-32-8oz/117707_0_0

Find a commercial AC tech who will most likely have nitrogen in his truck. Pressure test the system with nitrogen. Fix all the leaks. Evacuate properly and charge with approx. 80% of the original R-12 charge.
 
R12 is not illegal and it is available. You just have to know where to look. I just bought 4 cans at our Lincoln Swap Meet a couple weeks ago for 10.00 a can. I have never seen an old R12 Mopar system that has been converted to R134 work worth a damn! Ask around, there is always some around, garage sales, always swap meets or someone like me that has about 75 lbs.

Yea I can find it on craigslist for about 25 bucks a can.
 
A/C service is something that requires a high degree of precision. You drained, flushed the compressor of all mineral and added polyalkylene glycol a.k.a. PAG with out replacing the dryer? A recipe for failure for sure. If you left any mineral oil in the system it's worse. Poly Ester oil is compatible with R12 and R134a and is much better suited to vintage retrofits. It is readily available in most auto part stores.

https://www.autozone.com/a-c-chargi...er-refrigerant-oil-with-ice-32-8oz/117707_0_0

Find a commercial AC tech who will most likely have nitrogen in his truck. Pressure test the system with nitrogen. Fix all the leaks. Evacuate properly and charge with approx. 80% of the original R-12 charge.

Well I didnt drain anything out of my system originally because there wasnt anything in there.
 
I've tried diy AC several times. I've gotten things to work, and then they fail again in short order.

Take it to a pro. Without any experience, it's very tough to know exactly what you're doing and whether it will work. In Vegas I'd look for a mobile guy who likes old cars..
 
Well I didnt drain anything out of my system originally because there wasnt anything in there.
You obviously have a leak or it wouldn't be empty. Unless you have a gauge set, a evacuation pump, and the correct oil and refrigerant you would be best to find a professional. And that's at a minimum. It takes special tools to diagnose and repair leaks.
 
Can I ask a question? Where is the heater door
In the heater box. Well in your case the heat/ac box.

Also do you have an external valve to shut the water flow to the heater core?, Not sure if that was stock in 68 or 69.
 
You obviously have a leak or it wouldn't be empty. Unless you have a gauge set, a evacuation pump, and the correct oil and refrigerant you would be best to find a professional. And that's at a minimum. It takes special tools to diagnose and repair leaks.

It's not empty right now I dont think, I can press this and stuff comes out now.

It was empty. I dont think the PO ever charged it after swapping this engine into the car.

20200321_120627.jpg
 
R12 is not illegal, however I believe it is out of production. You can still buy it but its expensive and you have to have the proper license to purchase.
I recently had to get a license just to buy a 30lb R134 so the laws are steadily changing.
Yes you must replace the dryer when converting from 12 to 134. The proper thing to do is replace it any time the system is opened. Also, R12 and R134 dryers use different dessicants in them. Pag oil and Ester oils should not be mixed so the system needs to be flushed.
Not much room for error when servicing and AC system. Sounds like you need to hire someone.
 
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