AC only turns on when damp/rainy - wiring?

[Jayson44]

my AC works like a charm when it's not hot and dry out. the light is constant, there's refrigerant, and the compressor works...only when it rains. it seems that maybe the wiring has an issue somewhere and if it's damp or humid out it works fine. my simple brain tells me that the wet/humidity helps complete the connection and turns on the compressor.

is that a thing? where's the first place I should look?

is there a way for me to run a new manual switch to the compressor and just bypass the one on the dash?

J.

 

[Jayson44]

any ideas about how this would work? wiring up a switch to the condenser?

J.

 

[MikeinNH67]

any ideas about how this would work? wiring up a switch to the condenser?

J.

Well, there is a common issue with the relay that runs it. It usually sticks closed and makes for a blinking light but maybe it could fail the other way too. Usually though, if the compressor is not kicking on in higher temps it's because you are slightly low on refrigerant. Ambient temperature changes the pressure in the system, there's multiple sensors that check the pressure, if out of spec it will not run.

 

[Jayson44]

Usually though, if the compressor is not kicking on in higher temps it's because you are slightly low on refrigerant.

the temp doesn't seem to matter. it's literally if it rains or not. it worked during the winter, I assume because of the snow.

also, I had Firestone run a test of the entire system because I thought it needed refrigerant when I first bought it. they said it was full and that the compressor wasn't turning on all the time. but when it does turn on, it's ice cold and I can see the stuff in the viewing glass just fine.

no blinking light, relay is fine, it just chooses when to turn on. all temps work great when it's on, auto and manual. it's just hit or miss when the compressor turns on.

J.

 

[MikeinNH67]

How do you know the relay is fine? I took the one apart that was affecting my AC and is was pretty crusty inside. There's multiple relays in there that are the same if you want to try swapping them. The thing with this compared to other relays is that it cycles constantly unlike say the fog light relay.

 

[Jayson44]

How do you know the relay is fine? I took the one apart that was affecting my AC and is was pretty crusty inside. There's multiple relays in there that are the same if you want to try swapping them. The thing with this compared to other relays is that it cycles constantly unlike say the fog light relay.

1) the light doesn't blink

2) I swapped it with another one that was working and it didn't affect it.

I suppose I could just buy a new one and try it, but swapping it didn't help so I just saved my cash.

J.

 

[MikeinNH67]

1) the light doesn't blink

2) I swapped it with another one that was working and it didn't affect it.

I suppose I could just buy a new one and try it, but swapping it didn't help so I just saved my cash.

J.

I believe the blinking light is when it is only stuck on not failing to turn on. You swapped it with another though so you'd think not the relay.

 

[4RunnerAquasport]

I am by no means even remotely experienced in this, and I saw your post the other day, but didn't think of this until now. I had been working on my 1st gen AC and watched several videos, and one of the potential issues was the Thermal expansion valve.
Is it possible that it's partially clogged and when the atmosphere is damp, that allows it to open? Kind of reaching here, but it might give you another avenue of troubleshooting. Good Luck!

 

[Jayson44]

I am by no means even remotely experienced in this, and I saw your post the other day, but didn't think of this until now. I had been working on my 1st gen AC and watched several videos, and one of the potential issues was the Thermal expansion valve.
Is it possible that it's partially clogged and when the atmosphere is damp, that allows it to open? Kind of reaching here, but it might give you another avenue of troubleshooting. Good Luck!

hmm...I've never heard of that. I'll have to look into it. thanks!

J.