Help! A/C low pressure sensor..jumper?

[marcus]

to all the gods of electronic.. my low pressure sensor is out and dont have money right now to fix it,, can i "jump" the low pressure sensor wire harness terminal to activate the compressor clutch so i can use my a/c for now..compressor works but wont activate due to low pressure sensor, pressure test was done and its fine.. anyone its about to get real hot in TdotO.. thanks

[CTScott]

To bypass the pressure sensor you would need a 10K resistor and a 6.4K resistor.

The sensor has 3 terminals, so on the connector that you pull off of it you would connect the two resistors as follows:

10K between the grey and black wires
6.4K between the yellow and black wires
(so one end of each would go to the black wire)

If there is really something wrong with the system, then the end result may be a much larger repair bill if you run it with the sensor bypassed.

[marcus]

thanks scott.. what other issues would i ran into by jumping..beside low coolant level which can damage compressor...i wish they sell just the pressure switch rather than the whole pipes which includes high and low pressure switch.. over $500 bucks

[CTScott]

Originally Posted by marcus

thanks scott.. what other issues would i ran into by jumping..beside low coolant level which can damage compressor...i wish they sell just the pressure switch rather than the whole pipes which includes high and low pressure switch.. over $500 bucks

You just lose low and high pressure indication, both of which can be catastrophic to the compressor.

It is a shame on not being able to buy the sensor separate. The part number on the other thread is correct, but you can't actually seem to order them anyplace. The other option would be to pick up the line or sensor at a junkyard.

[marcus]

im pretty sure just the low pressure switch is not working, high pressure should still shut off the compressor during WOT.. im still leaning into checking the ambient sersor as well..

[CTScott]

Originally Posted by marcus

im pretty sure just the low pressure switch is not working, high pressure should still shut off the compressor during WOT.. im still leaning into checking the ambient sersor as well..

It is a single pressure transducer that feeds the pressure reading to the AC ECU, which then decides if it is low, high, or just right.

[marcus]

Originally Posted by CTScott

It is a single pressure transducer that feeds the pressure reading to the AC ECU, which then decides if it is low, high, or just right.

so ur saying by jumping the low pressure switch harness thats automatically jumping the high pressure as well?? men this is getting too complicated.. appreciate the input though..

[CTScott]

Originally Posted by marcus

so ur saying by jumping the low pressure switch harness thats automatically jumping the high pressure as well?? men this is getting too complicated.. appreciate the input though..

There is just one sensor (not a switch or switches, but a device that changes resistance based on pressure). That is why the two resistors, rather than jumpers are required to bypass it.

[marcus]

ok heres the pressure switch from toyota part# 499000-7141

[marcus]

499000-7880 - oil pressure switch part#
499000-7141 - a/c pressure switch part#

but this 2 could be the same.. i dunno.

now my question is how to test this switch to see if its working??

[CTScott]

Originally Posted by marcus

499000-7880 - oil pressure switch part#
499000-7141 - a/c pressure switch part#

but this 2 could be the same.. i dunno.

now my question is how to test this switch to see if its working??

The fact that the part number are different most likely means that the characteristics are different as well. To test it (and your existing one) you can measure the resistance between the pins that connect to the yellow and black wires and between the pins that connect to the grey and black wires.

By the way, I just happen to have a perfect sensor (off an 08 with 30,000 miles) in my hand at the moment that I harvested this morning.

[marcus]

lol ill take you up on that sensor my guy called and said hes got another one to give me incase the one i have wont work.. thanks ctscott

[Chrisholcroft]

My 07 yaris sounds very similar to your issue, the green light on the dash is illuminated but there isn't any power to the compressor solenoid. I'm wondering what readings I should have at the solenoid?