AC Problem Diagnosis Help - Not Blowing Cold Air
Instructor
Joined: Nov 2020
Posts: 145
Likes: 28
From: Colorado Springs
Curious...why the castellated nut directly above the low pressure valve? All my research suggests replacing both the drier and orifice tube when converting to r134a. Also the old o-rings are not compatible with the r134a compressor oil. Replace them. Some say the size of the r134a molecules will creep through the hoses so new hoses have a barrier to prevent that. All in all I replaced everything except the evaporator. It did get a washing out with MEK to remove as much of the old oil as I could while I rebuilt the heater box. Overall a big job. Just changing the ports is only the beginning. Lonnie
Drifting
Joined: Aug 2019
Posts: 1,341
Likes: 225
I wouldn't be concerned about new hoses. Over time the inside of the hoses develop a coating because the oil penetrates the rubber. O rings... yes.
Not sure why everyone is concerned about that clutch. It seems to be working, I'd be more concerned with what's going on inside charge wise, and why it isn't cycling. If you had gauges, you would see what the low side is at, If it pulls down to 28-32, then it should cycle. If the previous guy hot wired that switch. then I would rule him out from any further repairs. Finally, I would NOT run the system at all until the proper charge is in the system. The gas carries oil throughout the system, and you could damage the compressor, if it hasn't been damaged already.
Not sure why everyone is concerned about that clutch. It seems to be working, I'd be more concerned with what's going on inside charge wise, and why it isn't cycling. If you had gauges, you would see what the low side is at, If it pulls down to 28-32, then it should cycle. If the previous guy hot wired that switch. then I would rule him out from any further repairs. Finally, I would NOT run the system at all until the proper charge is in the system. The gas carries oil throughout the system, and you could damage the compressor, if it hasn't been damaged already.
Le Mans Master
Joined: Jun 2019
Posts: 7,670
Likes: 2,474
From: Indiana
I wouldn't be concerned about new hoses. Over time the inside of the hoses develop a coating because the oil penetrates the rubber. O rings... yes.
Not sure why everyone is concerned about that clutch. It seems to be working, I'd be more concerned with what's going on inside charge wise, and why it isn't cycling. If you had gauges, you would see what the low side is at, If it pulls down to 28-32, then it should cycle. If the previous guy hot wired that switch. then I would rule him out from any further repairs. Finally, I would NOT run the system at all until the proper charge is in the system. The gas carries oil throughout the system, and you could damage the compressor, if it hasn't been damaged already.
Not sure why everyone is concerned about that clutch. It seems to be working, I'd be more concerned with what's going on inside charge wise, and why it isn't cycling. If you had gauges, you would see what the low side is at, If it pulls down to 28-32, then it should cycle. If the previous guy hot wired that switch. then I would rule him out from any further repairs. Finally, I would NOT run the system at all until the proper charge is in the system. The gas carries oil throughout the system, and you could damage the compressor, if it hasn't been damaged already.
because of the 19 second mark in the second video you can clearly see the clutch starting to slip and or rotation change from fast slow to fast again...and it would be good to know if working properly or not...
of course gauges are first..noone disputes that
Last edited by interpon; May 25, 2021 at 06:50 PM.
Le Mans Master
Joined: Jun 2019
Posts: 7,670
Likes: 2,474
From: Indiana
Le Mans Master
Joined: Jan 2001
Posts: 6,746
Likes: 1,387
I've done several R-134a conversions and I installed, evacuated, and charged my Hot Road a/c system myself.
On the conversions I've done it both ways: 1) the long way with major components replaced, o-rings, orifice vlv, and/or control valve, dessicant/dryer, etc......and I've also done the quick easy where all I did was swap fittings, evacuate (was pretty much empty already) and recharged. Every one of them has worked and cooled to 40 degrees.
BUT you really need to start by finding out what is going on with your system. Personally I think it is well worth having the a/c gauges and a vacuum pump. The vacuum pump comes in especially handy on troubleshooting the vacuum systems on a C3 corvette too.
You really need to get some gauges and get some readings. We could even tell what the compressor with those gauges. The we can all be more helpful in assisting you in troubleshooting.
On the conversions I've done it both ways: 1) the long way with major components replaced, o-rings, orifice vlv, and/or control valve, dessicant/dryer, etc......and I've also done the quick easy where all I did was swap fittings, evacuate (was pretty much empty already) and recharged. Every one of them has worked and cooled to 40 degrees.
BUT you really need to start by finding out what is going on with your system. Personally I think it is well worth having the a/c gauges and a vacuum pump. The vacuum pump comes in especially handy on troubleshooting the vacuum systems on a C3 corvette too.
You really need to get some gauges and get some readings. We could even tell what the compressor with those gauges. The we can all be more helpful in assisting you in troubleshooting.
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Thread Starter
Intermediate
Joined: Mar 2021
Posts: 26
Likes: 6
From: Tampa, FL
Update: Took the Vette to an AC Repair shop in Clearwater, FL that has been in business for over 30 years. Solid online reviews. Spoke with them last week and explained what had been done previously. They assured me that they have extensive experience converting systems from r12 to r134a and they doa lot of work on classic cars. I was told that the compressor was bad. They replaced with a new compressor, orifice and o rings. They called me to tell me it was ready and I asked how cold it was blowing. Guy said in the 50s. The thermostat I brought with me and plugged into vent never read below 80 during my 15 minute drive home. I then parked the car in the garage and ran the ac for another 10 minutes. Temp stayed the same. Very frustrated and I called and left a message for the owner to call me.
At this point I’m ready to have them take out the Freon and I’ll bolt on a new condenser and evap myself.
At this point I’m ready to have them take out the Freon and I’ll bolt on a new condenser and evap myself.
Le Mans Master
Joined: Jun 2019
Posts: 7,670
Likes: 2,474
From: Indiana
Update: Took the Vette to an AC Repair shop in Clearwater, FL that has been in business for over 30 years. Solid online reviews. Spoke with them last week and explained what had been done previously. They assured me that they have extensive experience converting systems from r12 to r134a and they doa lot of work on classic cars. I was told that the compressor was bad. They replaced with a new compressor, orifice and o rings. They called me to tell me it was ready and I asked how cold it was blowing. Guy said in the 50s. The thermostat I brought with me and plugged into vent never read below 80 during my 15 minute drive home. I then parked the car in the garage and ran the ac for another 10 minutes. Temp stayed the same. Very frustrated and I called and left a message for the owner to call me.
At this point I’m ready to have them take out the Freon and I’ll bolt on a new condenser and evap myself.
At this point I’m ready to have them take out the Freon and I’ll bolt on a new condenser and evap myself.
rather change 10 compressor than that accumulator
Last edited by interpon; May 29, 2021 at 05:53 PM.
Drifting
Joined: Aug 2019
Posts: 1,341
Likes: 225
As a guide with 134, you should see about 30 deg F below ambient. Is the compressor cycling? The lines going into and out of the evaporator should be cool, and feel about the same.
Don't guess for them, They should ne able to diagnose it.
Don't guess for them, They should ne able to diagnose it.
Drifting
Joined: Aug 2019
Posts: 1,341
Likes: 225
Thread Starter
Intermediate
Joined: Mar 2021
Posts: 26
Likes: 6
From: Tampa, FL
- Both lines going in/out of evap are cool to the touch and feel the same
- The compressor cycled initially for about the first 3 minutes then seemed to not cycle after that.
- Belt seems loose to me
- Lots of condensation having only run the ac for about 7 minutes total
Le Mans Master
Joined: Jan 2001
Posts: 6,746
Likes: 1,387
That is some crappy work if they left the belt that loose. Hard to believe they have 30 years of experience. Take it back and tell them to fix it, to make it blow cold, or to give you your money back.
If that's as good as their service gets then you might be better off doing it yourself.
If that's as good as their service gets then you might be better off doing it yourself.
Le Mans Master
Joined: Jun 2019
Posts: 7,670
Likes: 2,474
From: Indiana
Tighten belt..
put thermometer in center vent..fan on low doors open..compressor should cycle when vent temperature cycles of anywhere between 34-42f...fat city...
the compressor should not cycle if hot and fan high...
Assumes heater shut off is working
condensation is good
put thermometer in center vent..fan on low doors open..compressor should cycle when vent temperature cycles of anywhere between 34-42f...fat city...
the compressor should not cycle if hot and fan high...
Assumes heater shut off is working
condensation is good
Last edited by interpon; May 30, 2021 at 05:04 PM.
Thread Starter
Intermediate
Joined: Mar 2021
Posts: 26
Likes: 6
From: Tampa, FL
UPDATE: Thanks again for everyone's comments on this. When first turned on, the compressor clutch engages and disengages about every 10 seconds and then engages less frequently for the next 4 minutes until it does not engage anymore.When it is first turned on and engaging frequently, the system cools to about 61 degrees (outside temp is about 85).