Absence of High Pressure/Low pressure Switch in car AC

[doctor]

What is harm if a 1996 Corolla does not have both High pressure switch and Low pressure switch in its AC system?Is it okay to run its AC without these two switches?One of the drawback I know is that the Fans will not run at full speed in Auto mode as there will be no signal to the fans from the high pressure line switch.What else can happen???

[Xulfiqar]

the high low pressure oval switch is about Rs 2300/- for a genuine one, its a very good safety device for the AC unit, the low pressure cuts out the compressor when gas pressure is too low as low gas means low circulation which means low oil circulation too - low oil will kill the compressor.

The high pressure switch can be rigged with a cut off relay to engage the fans full speed whenever the compressor is running - this is only done when you are not able to locate such a switch as a spare part.

But I am sure you can get it quite easily so dont skimp on it. When everything works original it will work properly.

[doctor]

Thanks.Actually the AC low and high pressure lines does not have any switch and I have two options, either to buy the whole pipe with the switch or to cut the pipe and weld the switch to it.

And what is the function of High pressure switch?And as you said, cut off relay can be installed instead of it, means it does not have any other function but just increasing fans speed?Or it has some other function?

the high low pressure oval switch is about Rs 2300/- for a genuine one, its a very good safety device for the AC unit, the low pressure cuts out the compressor when gas pressure is too low as low gas means low circulation which means low oil circulation too - low oil will kill the compressor.

The high pressure switch can be rigged with a cut off relay to engage the fans full speed whenever the compressor is running - this is only done when you are not able to locate such a switch as a spare part.

But I am sure you can get it quite easily so dont skimp on it. When everything works original it will work properly.

[doctor]

@ Xulfiqar

Your reply awaited for post number 3.

[Xulfiqar]

the switch is usually placed on the low side line near the evaporator outlet pipe, it would be a gray oval piece with 4 wires. If you dont have the switch then look for the wiring it should have a gray oval connector unused or if the wiring connector has been cut off look for a bunch of wires taped up. All corollas have that switch.