A\C on, soft popping behind the console?

[Kenny_Z]

Normally I have the radio on so I don't hear this but today my brother and I were in the car and I could hear a soft popping every few seconds behind the console. It was only on with the AC running. I don't recall hearing that last summer but I hadn't been into the console area yet. Did I break something?

[jawn101]

Normally I have the radio on so I don't hear this but today my brother and I were in the car and I could hear a soft popping every few seconds behind the console. It was only on with the AC running. I don't recall hearing that last summer but I hadn't been into the console area yet. Did I break something?

Could be the A/C and fan relays cycling... are you sure it was from in front of you and not from the relay compartment?

Every few seconds is pretty frequent for that to cycle though, is the A/C working well?

[DMCMW Dave]

Normally I have the radio on so I don't hear this but today my brother and I were in the car and I could hear a soft popping every few seconds behind the console. It was only on with the AC running. I don't recall hearing that last summer but I hadn't been into the console area yet. Did I break something?

Compressor cycling, you are probably hearing the fan relay.

[Bitsyncmaster]

The low pressure switch makes a click sound when it opens.

But it sounds like you are low on freon if it's every few seconds.

[David T]

It could also be the cooling fan circuit breaker. You should check to make sure you have the relay upgrade kit. If it is just the fan relay, you may be cycling a little too fast. That would be a sign that you are a little low on refrigerant.
David Teitelbaum



The low pressure switch makes a click sound when it opens.

But it sounds like you are low on freon if it's every few seconds.

[Kenny_Z]

It's definitely behind the console, it is louder there when I put my ear up to it. The previous owner put in a fan relay kit that seems to be functioning properly.

The AC is not as cool as it was last year. I noticed that when the popping lessened after driving for awhile today the ac blew colder. Looks like she's going back into the AC shop for awhile. Thanks guys, I appreciate the help.

[David T]

If "behind the console" you mean the center of the dash behind the interior comfort controls and radio, there is not supposed to be any relay there. It must be something added by a DPO. Overly fast cycling will definitely reduce the cooling capacity. My previous post referred to the fuseblock area behind the rear passenger seat.
David Teitelbaum



It's definitely behind the console, it is louder there when I put my ear up to it. The previous owner put in a fan relay kit that seems to be functioning properly.

The AC is not as cool as it was last year. I noticed that when the popping lessened after driving for awhile today the ac blew colder. Looks like she's going back into the AC shop for awhile. Thanks guys, I appreciate the help.

[Kenny_Z]

There's no relay back there. I never saw one when I took it apart. The sound is definintely coming from behind the comfort controls below the radio though. It's not a click like a relay, it's a soft popping much like an air bladder that's got a low pressure release valve. You can mimic the sound by saying "poff." I'd take a recording but my phone doesn't pick up the sound.

[jawn101]

Do you feel hot air coming out near your feet while the A/C is on? You may be the victim of an old piece of foam (called a "tube seal") at the rear of the heater box, between the heater box and the firewall. If you lay on your back in the driver's footwell, reach to the right of the accelerator pedal. Feel along the center of the heater box between it and the firewall (more or less in line with the A/C mode switch) for either a piece of dried up old foam, or if the foam is completely deteriorated, a hole in the heater box. That foam is meant to fill the hole. Not entirely sure what the hole is for, but the recommended fix is to slap a piece of duct tape over it. The noise you hear may be that foam flapping around.

The seal is #19 on this diagram http://store.delorean.com/c-302-7-1-1-heater.aspx but is shown in the incorrect location. It's right in the center of the heater box, on the back side.

[Kenny_Z]

I'll take a look tomorrow morning before work. I was going through the online store in DMCH looking at diagrams of the AC system. Is it possible I have a vacuum leak and what I'm hearing is the diaphragm popping back to place?

[jawn101]

Could be, you should know by now that anything's possible.... :) Diagnosis by sound is hard enough when you're actually hearing the sound though, so diagnosis by onomatopoeic description is nearly impossible.

[Kenny_Z]

Yeah, I thought maybe it someone else had heard the same sound before they may have had an idea of what to check.

[Notifier]

I hear a sound, don't know if it's the same one you are describing, while the AC is running. Best way I can describe it is someone taking a small mallet and tapping lightly on the bottom of a metal coffee can. Sounds like it's coming from behind or under the seats. Very faint and intermittent, have to have the radio off to hear it. AC runs fine from what I can tell.

[jawn101]

I hear a sound, don't know if it's the same one you are describing, while the AC is running. Best way I can describe it is someone taking a small mallet and tapping lightly on the bottom of a metal coffee can. Sounds like it's coming from behind or under the seats. Very faint and intermittent, have to have the radio off to hear it. AC runs fine from what I can tell.

I'd bet you what you're hearing is the compressor clutch kicking on and off.

[Kenny_Z]

I think you're right Jawn. I finally had some time to put a cheap gauge I have on the low pressure side and this is what I found.


http://www.youtube.com/watch?v=QRxSaELArK8&lc=N17xrzYwwWWaBdWrs0kj1_MXfgQjw-sdvWp9NSsdN54&feature=inbox

I thought the popping was too frequent to be the compressor but it matches up to this perfectly. I'm guessing this means I'm low on freon?

[jawn101]

I think you're right Jawn. I finally had some time to put a cheap gauge I have on the low pressure side and this is what I found.

I thought the popping was too frequent to be the compressor but it matches up to this perfectly. I'm guessing this means I'm low on freon?

I'm not an A/C expert so hopefully someone like Ron can chime in on why it might cycle too much. If you were really low on freon though, the compressor shouldn't engage at all. Something else may be up here. Does it blow cold?

[DMCMW Dave]

If you were really low on freon though, the compressor shouldn't engage at all. Something else may be up here. Does it blow cold?

Somewhere between "full" and "empty" is "low". "low" is where it will cycle too often. "empty" is where it won't cycle at all. Well, not really empty, but pretty close.

[Kenny_Z]

Cooler but not cold. I haven't stuck a thermometer in there but it can't be less than a 5 degree difference from the ambient air. I get more relief by rolling down the windows.

[Ron]

If you don't know a good AC person, you can probably get a set of decent gauges for the price of a top off...

[Kenny_Z]

The AC guys I took it to before didn't do a bad job but I think I'll try to pick up the tool at harbor freight so I can learn a little about the system. Thanks everyone.

[Kenny_Z]

I bought a set of gauges at HF today and put them on the D. After following the instructions (and a youtube video), I let the car properly warm up and held the idle at 1500 rpm. My compressor stopped cycling so much. However, I saw that both the high and low side were holding steady at about 130psi. The air from the vents was getting increasingly warmer. Both the high and low pressure adapters were painfully hot. I had to remove them with a shop rag.

According to the video the normal cause of the equalized pressure is a stuck open expansion valve. So what does that equate to in a Delorean's system? I do not see anything labeled expansion valve on DMCH's site.

[Bitsyncmaster]

I bought a set of gauges at HF today and put them on the D. After following the instructions (and a youtube video), I let the car properly warm up and held the idle at 1500 rpm. My compressor stopped cycling so much. However, I saw that both the high and low side were holding steady at about 130psi. The air from the vents was getting increasingly warmer. Both the high and low pressure adapters were painfully hot. I had to remove them with a shop rag.

According to the video the normal cause of the equalized pressure is a stuck open expansion valve. So what does that equate to in a Delorean's system? I do not see anything labeled expansion valve on DMCH's site.

Was the compressor running? Sounds like it the compressor is not pumping. Our system does not use an expansion valve. It uses an orifice so it can't stick open.

[David T]

Sounds like your system is full of air, not refrigerant. A system full of air would show high and low side pressures roughly equal because it would not go through a phase change.
David Teitelbaum





Was the compressor running? Sounds like it the compressor is not pumping. Our system does not use an expansion valve. It uses an orifice so it can't stick open.

[Kenny_Z]

I bought a vacuum pump the same time I bought the gauges so I could try to vacuum it out. The compressor was running. Static pressure tests without the engine running show a much lower PSI so I think the compressor is doing something.

[David T]

The proper order is to pressurize the system and test for leaks. After repairing any you find you replace the dryer/accumulator and retest the connections you did. Now you vacuum and then charge with refrigerant. If you have the original hoses you should just replace them. You should also drain all of the oil out of the compressor and refill with fresh. If the insides look clean (not all gunked up and black) you should be OK with this. Static you had enough pressure to trip the low pressure switch to get the compressor to run. It heated up the air and raised the pressure. To get that much air in the system you have large leaks.
David Teitelbaum




I bought a vacuum pump the same time I bought the gauges so I could try to vacuum it out. The compressor was running. Static pressure tests without the engine running show a much lower PSI so I think the compressor is doing something.

[Kenny_Z]

Sounds like I should put her on blocks this summer and do the little things I've been putting off with the parts I already bought. Unfortunately today my company announced they will be closing up shop on the 21st of June. I can't spend any money on my projects now. Time to job hunt.

Thanks for the information everyone, I'll bookmark this thread when times aren't so troubling :\

[jawn101]

Sounds like I should put her on blocks this summer and do the little things I've been putting off with the parts I already bought. Unfortunately today my company announced they will be closing up shop on the 21st of June. I can't spend any money on my projects now. Time to job hunt.

Thanks for the information everyone, I'll bookmark this thread when times aren't so troubling :\

Sorry to hear it mate, best of luck to you.