Sounds like Relay Popping ever 5 seconds behind cluster

[Mr. Tasty]

I have a 1987 eta, and recently I have been hearing a popping sound, like a relay happening behind the cluster. My air conditioning is also not working at the minute. It blows, but just ambient air temperature. Could this be the blower motor going out?

Also a somewhat relatable question. My car has been revving after I drop it out of gear from braking. It will rev to 1300, drop, 1300, drop, 1300, and slowly drop to about 800 rpm. I could get it to stop doing it by turning on the air conditioning. It would hold a steady 750 rpm. With the current relay popping and air conditioning stopping, I cannot turn on the a/c to resolve my problem. Any clue? Sounds electrical rather than mechanical.


Any help is gratefully appreciated.

[Mr. Tasty]

also the revving only happens when the car is warmed up. Something to do to increased resistance on an electrical part? Maybe the throttle position sensor?

[dnguyen1963]

As for engine revving when the engine is warm, I think you have a small vacuum leak somewhere that only a smoke test can detect. I'll leave the A/C problem to the experts on this forum.

[Mr. Tasty]

it just seems odd that I could "cure" it by turning on the air conditioning previously.

[Mr. Tasty]

maybe by turning on the air conditioning, it raised the rpm and kept it steady? who knows. I am completely puzzled.

[dnguyen1963]

Raising the rpm high enough might just compensate for the small leak...maybe.

[5Toes]

my e34 has a popping noise like you describe

[Mr. Tasty]

well a/c works. Seems my button has some corrosion or something. Still, I am able to lower the rpm to 750 with a/c. Common vacuum leak I suppose. What should my rpm be at with a/c on? Am I good?

[paperplane94]

Sounds like the popping noise is a flap motor trying to close, then when you turn the a/c on its already open so it stops trying to open.

Happens all the time on the E32/E34. I would imagine the E30 has something similar.

[Mr. Tasty]

its happening again, my air conditioning worked earlier today. Hop in my car again to do an errand, and no air conditioning plus popping noise. Sounds to be coming from below and to the left of the kick board on the driver's side. This is really puzzling.

[Mr. Tasty]

think the problem?

would explain working, and then not.

[5Toes]

Sounds like the popping noise is a flap motor trying to close, then when you turn the a/c on its already open so it stops trying to open.

Happens all the time on the E32/E34. I would imagine the E30 has something similar.

how do you fix?

[Mr. Tasty]

car is doing again. It is making the same popping noise that triggers the a/c. Think it could be the bad switch? or maybe something under the dash? I do have to lightly smack the dash to get the tach and fuel efficiency going.

[dnguyen1963]

There is some serious arcing in that switch. The popping noise is probably the result of that.

[Mr. Tasty]

this is the relay that keeps clicking. All connections look clean though... any idea?