Vintage Air Mini Gen II - A/C Not Functioning

[Pasha Saleh]

Finally got the heat side of this unit working (bad potentiometer) and now can't get A/C to blow cold. Fan motor works correctly at all 3 speed settings but doesn't seem that the compressor every switches on. System was vacuumed, leak tested, and charged.

The Vintage Air Mini Gen II has a "Mode" switch that selects where the air comes out (floor vent/defrost vent/etc). As this does not apply to the GT40, I removed this switch and rewired according to what the Vintage Air tech told me. Now, when I turn on the A/C knob, I hear the "click" but the compressor does not seem to be engaging.

Question: Should the A/C compressor click on even when the engine is not running? If I turn the key on, I have power to the blower fan so wanted to test by ear whether or not the A/C clutch is engaging without the noise of the engine running.

Assuming the tech did not lead me astray in the rewiring of the circuit to accommodate removal of the Mode switch, what else could be going on and where should I check?

My wiring harness is all shrink wrapped and neatly hidden away so would strongly prefer to test the easy things first before cutting off the trinary switch, etc. To that end, where should I start testing for power/continuity?

Here's what Vintage Air had me do to remove the Mode switch:

• Attach Pink wire from Mode Switch prong "B" and Blue Wire from Mode switch prong "M" to Black wire on Blower switch prong "C".

I ended up with a Yellow wire coming from the Control Module with nowhere to go and was told to cut that off.
I was also told to cut off the Green wire because I don't have a defrost circuit.

Anyone else removed the Vintage Air Mode switch and did I do this correctly?

 

[Kyle]

How did you charge the system if the AC compressor never worked? Yes 12v to the compressor will engage the clutch. So to test just unplug the wire at the compressor going to the controls, start engine, run fan on high, then apply 12v to that compressor wire for a bit directly and see if it starts blowing cold air or even engages.

If it does then clearly the fault is in your wiring you did.

 

[Joel Heinke]

To add to the post above...I have a Vintage Air Mini Gen II in a homebuilt car and was recently working on it. I do still have the Mode switch as part of the AC system so I can't give input on your rewiring of it. The car had leaky AC hoses (I can't recommend SS AC hoses as they all started to leak eventually and I replaced them with good ole rubber AC hoses) and each time a hose started to leak it lost all the R134 pressure. In order to recharge the AC after replacing hoses, I had to jump 12V into the AC compressor wire in order to engage it. I was recharging from the low pressure side of the system. The AC compressor needs to be engaged to properly charge the system when doing it this way. The system in my car has a binary switch which sensed the lack of pressure and thus was not relaying the 12V power to the AC compressor. Once the system had enough pressure in it for the binary switch to be happy, I could remove the jumper going to AC compressor and the Vintage Air AC control/wiring took over fine. It wasn't intuitive to me that a jumper would be required until I fully understood what the binary switch was doing but now I know.

 

[Pasha Saleh]

Thanks, Joel, for your quick reply! I followed the charging instructions that Vintage Air provided and had a local shop (that specialized in hot rods and classics) hook it up to their system, which pulled a vacuum, ran a 10 minute leak test, then added the refrigerant and oil. It was a big automated machine that ran for about half an hour. Are you saying the engine should have been running this whole time to fill the system? The VA charging instructions didn't mention anything about that.

 

[Brian]

An OEM system can be charged without the car running, but with a custom hot rod install, it's impossible to know what the exact weight of the refrigerant charge is without guesswork determined by running it.

 

[Joel Heinke]

Thanks, Joel, for your quick reply! I followed the charging instructions that Vintage Air provided and had a local shop (that specialized in hot rods and classics) hook it up to their system, which pulled a vacuum, ran a 10 minute leak test, then added the refrigerant and oil. It was a big automated machine that ran for about half an hour. Are you saying the engine should have been running this whole time to fill the system? The VA charging instructions didn't mention anything about that.

I'm just an DYI guy and not an AC expert. I do know that when charging an AC system at home, it's done through the low pressure port and this requires the AC compressor to be running in order to cycle the Freon through the system.

A 10 minute leak test sounds way too short to me. When the Vintage Air system in my car was initially tested, the test was conducted for a couple of hours. Even then it didn't appear to be leaking but there were slow leaks that took about a week for the AC system to loose it's charge. In my case, it was a Stainless Steel braid AC hose that was leaking very slowly but there can be other things that leak slowly as well.

Given my experience with AC stuff, the first thing I'd recommend you do is check to see if your AC system still has pressure in it. If not, that would explain why the AC compressor isn't being engaged. The binary/trinary switch is a safety measure keeping the AC compressor from running when the Freon in the system is inadequate.

 

[Nick]

A 10 minute leak test sounds way too short to me. When the Vintage Air system in my car was initially tested, the test was conducted for a couple of hours. Even then it didn't appear to be leaking but there were slow leaks that took about a week for the AC system to loose it's charge. In my case, it was a Stainless Steel braid AC hose that was leaking very slowly but there can be other things that leak slowly as well.

Apologies for the thread hijack as I have a similar issue how did you track down the slow leaks? thanks

 

[Brian]

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They also sell a UV die you can put in the refrigerant circuit, then use a black light and find the leaks.

 

[Paul Hendrickx]

Hi,
I used this sometimes to help people understand the effects of mal function on air con with gauges en thermometer... you should be able t pin point ...
hope it is of some use?
Paul

 

[Joel Heinke]

Apologies for the thread hijack as I have a similar issue how did you track down the slow leaks? thanks

I used the UV die to find the leaks in mine. The die stays in the system so on subsequent leaks from various SS braid hoses, it was fairly obvious where the leak was because there was bright green die stain where the hose met the fitting on the end of it.

 

[Pasha Saleh]

Thank you, all! I will get into it this weekend and see what I find.

 

[Pasha Saleh]

So, all circuits check out fine and bypasing the trinary switch causes both the compressor to click on and the radiator fan to run. Pressing down on the Schraeder valve where the trinary screws into results in a very faint hiss so it seems all the refrigerant has leaked out.

My fill ports are right on the compressor which is nearly impossible to access -- needs the car to be jacked up, belt tensioner removed and the compressor swung out of the way to fill it -- a real pain. What's the best way to check for a leak so I don't have to keep refilling the system?!

 

[DaveC]

You're going to have to charge it again with refrigerant that has UV dye, run it, and use a UV flashlight to find the leak. Probably a $0.25 seal, possibly a loose fitting if it's a new system.

 

[DaveC]

System was vacuumed, leak tested, and charged.

Are you sure about this? Odd that you are losing refrigerant in a checked-over system. The only moving part in the system is your compressor. My bet is you have a bad compressor. Unless you took a stone to the condenser or something, did you look in the grille? I had a new compressor that was bad once.

 

[Joel Heinke]

So, all circuits check out fine and bypasing the trinary switch causes both the compressor to click on and the radiator fan to run. Pressing down on the Schraeder valve where the trinary screws into results in a very faint hiss so it seems all the refrigerant has leaked out.

My fill ports are right on the compressor which is nearly impossible to access -- needs the car to be jacked up, belt tensioner removed and the compressor swung out of the way to fill it -- a real pain. What's the best way to check for a leak so I don't have to keep refilling the system?!

It it were my car, I'd add in an accessible service port (especially on the low pressure side) that can be used when the AC compressor is running. That way you can re-charge the system yourself and put in the UV die so you can find the leak(s). There are hose ends available that include a service port so you can do this by having a custom AC hose built making sure the newly added service port is easily accessible. For the AC system I recently had to troubleshoot, it had multiple leaky hoses and I had to recharge the system a few times in order to find all the leaks. Unfortunately, it wasn't one and done. If I had to run the car back to an AC shop multiple times, it would have been very frustrating, time consuming and expensive. Now that the AC system has held a charge for several months, I can take it in to get it "fully charged" (i.e. have the trapped air that resulted from hose swaps removed) with confidence that it won't have to go back to the AC shop very soon.

 

[Brian Kissel]

Very informative post Joel, Thanks for your input.

Regards Brian

 

[Pasha Saleh]

Are you sure about this? Odd that you are losing refrigerant in a checked-over system. The only moving part in the system is your compressor. My bet is you have a bad compressor. Unless you took a stone to the condenser or something, did you look in the grille? I had a new compressor that was bad once.

Hi Dave,

It was hooked up to this automatic machine that pulled vacuum, checked for leaks for 10 minutes, then pumped in the pre-programmed quantity of fluid. The A/C seem to work on my way home from the shop but it was February and 40 degrees outside! that was also 6 months ago and I haven't turned it on since then until just the other day when I realize there is inadequate pressure to trip the trinary. Isn't it possible that there was a small, slow leak that caused the refrigerant to escape over several months? I could see it passing a few minutes leak test that way.

 

[Pasha Saleh]

It it were my car, I'd add in an accessible service port (especially on the low pressure side) that can be used when the AC compressor is running. That way you can re-charge the system yourself and put in the UV die so you can find the leak(s). There are hose ends available that include a service port so you can do this by having a custom AC hose built making sure the newly added service port is easily accessible. For the AC system I recently had to troubleshoot, it had multiple leaky hoses and I had to recharge the system a few times in order to find all the leaks. Unfortunately, it wasn't one and done. If I had to run the car back to an AC shop multiple times, it would have been very frustrating, time consuming and expensive. Now that the AC system has held a charge for several months, I can take it in to get it "fully charged" (i.e. have the trapped air that resulted from hose swaps removed) with confidence that it won't have to go back to the AC shop very soon.

That's a really good idea -- thanks for the suggestion, Joel! I don't know the high side from the low side! In which line(s) would I install these fittings? The most accessible place would be in the snorkel where I have mounted the dryer. Could I just unscrew a line from either side of the dryer and install a fill port there?

Also, how about one of those "sniffer" tools? Amazon has them for $20 and it claims to work without needing dye.

 

[Paul Hendrickx]

That's a really good idea -- thanks for the suggestion, Joel! I don't know the high side from the low side! In which line(s) would I install these fittings? The most accessible place would be in the snorkel where I have mounted the dryer. Could I just unscrew a line from either side of the dryer and install a fill port there?

Also, how about one of those "sniffer" tools? Amazon has them for $20 and it claims to work without needing dye.

the thinnest line is the high pressure line the bigger one is the return
put one connector(charging port) before the evaporator ( on the high pressure line) and the other. after the the evaporator...
Paul

 

[Brian]

The sniffers are far more effective than the soapy bubbles, but the die will accumulate over hours, days or weeks when a real slow leak may be tedious to sniff around every fitting to find. And in a dark garage with a UV light, you can see the die from across the garage.

I've used mine to verify I had a hole in an evap by sniffing in the vent after the car had sat for a few hours.