Oil pressure gauge problems!!!

[UP THE RED VS]

So I've installed an oil pressure gauge along with volts and water temp and they both work fine, it's just the oil pressure gauge I'm having problems with, I don't have a clue why but when I turn the aircon on the gauge drops to about 30psi and originally thought voltage drop so I rewired it but still no luck, next I tried powering straight of the battery but still happened and then I tried off of my mates cars battery and still when I turn the aircon on it drops?
I wouldn't think the aircon would drop oil pressure?
Any ideas more then welcome willing to try anything at this stage haha

 

[Immortality]

Faulty gauge?

Talk to the supplier and see what they say.

Just out of curiosity, where is the oil pressure sender fitted?

How much is the oil pressure dropping?

 

[delcowizzid]

if its a 2 wire sender run the earth for the gauge and the earth for the sender to a bolt on the engine or earth bias will make the gauge go weird

 

[UP THE RED VS]

It's hooked up using a t-peice adaptor and it's only got the 4 wires, power, accessories, earth and the signal, no seperate earth and its dropping from 50psi down to 28psi

 

[delcowizzid]

so 1 wire sender earthed via the sender body

 

[Immortality]

Faulty sender possibly?

 

[Nut Kracker]

Does the oil pressure drop that much (with the A/C on), when the engine is above idle.....say for example; driving at cruise speed, or around town?
Or does it come up to normal pressure?

If this is only happening at idle, are the revs dropping below normal idle, when you turn on the A/C? (thus reducing the oil pressure).

 

[UP THE RED VS]

When driving the gauge pretty much stay around 30-40psi unless really upping it, it may get to get 50 something but that's about it

 

[Immortality]

That doesn't sound right for a ecotec engine. Thought they ran more oil pressure than that.

 

[delcowizzid]

Run the gauge earth to the engine block even with a temporary length of wire out the window