bypassing pressure switch for air conditioning - how safe

How safe is it to bypass the pressure switch temporarily. My pressure switch got physically damaged over the winter and the wired connection ripped off of the "sender" if you will. Soldering the wires back on the sender in place won't work, it's wasted. I plan on repairing it correctly this weekend but we are in for hot weather this week and I have to spend a lot of time in the car. If I jumper the connection at the connection plug can I cycle my air on and off while driving and not damage anything? I don't really know how the compressor cycles on and off during normal usage or if it does at all. The car is a 2005 Infiniti G35 sedan, 6 speed manual of course.

If the system is otherwise in good shape it should be no problem. Just remember. One of the jobs of the switch is to protect the system in case of low refrigerant.

In reply to NJArch:

Under normal conditions the pressure switch doesn't cycle the compressor. That is done by there thermostat. Many systems have both high and low pressure switches to protect the compressor from very low and very high pressures. But some have a binary or trinary switch which is supposed to protect against high and low pressures, but really doesn't do a good job on the low side. In your case, if your system is working properly, you should be able to bypass the switch temporarily until you can replace it.

Depends on the system. Real simple systems will cycle based off of the low side to keep the evaporator from icing over, with a fixed orifice instead of a variable valve.

The Infiniti does use an expansion valve so you should be okay to just leave it unplugged, or shorted, depending on which way makes the system work.

In reply to Knurled:

While I'm not familiar with this specific system, the use of an orifice tube in place of the expansion valve does not directly relate to controlling cycling. The purpose of an orifice tube or a TXV are to regulate the refrigerant flow. Its just a cheap and less effective way of controlling superheat. The thermostat is what is used to prevent freezing of the coil by cycling the compressor when needed.

bravenrace wrote: In reply to Knurled: While I'm not familiar with this specific system, the use of an orifice tube in place of the expansion valve does not necessarily mean it doesn't have a thermostat. The purpose of an orifice tube or a TXV are to regulate the refrigerant flow. The thermostat is what is used to prevent freezing of the coil. If Infiniti is using pressure switches to cycle the compressor, then they are doing it very, very wrong, and he shouldn't bypass the pressure switch because it may damage the compressor.

For what it is worth my pressure switch is located near the condenser and it appears complicated. Like I said before the female plastic connector busted off the pressure switch and you can kind of see inside and there is a tiny circuit board integrated into the top of the switch. The sensor itself is like $70 from Rockauto.

In reply to NJArch:

That would be either a high pressure switch or a multi-function switch like a binary or trinary. How many wires are going to it?

bravenrace wrote: In reply to Knurled: While I'm not familiar with this specific system, the use of an orifice tube in place of the expansion valve does not directly relate to controlling cycling. The purpose of an orifice tube or a TXV are to regulate the refrigerant flow. Its just a cheap and less effective way of controlling superheat. The thermostat is what is used to prevent freezing of the coil by cycling the compressor when needed.

Ayup... and the low side pressure switch works in the same function as a thermostatic switch. If the low side pressure never drops below 30psi (or whatever the specific refrigerant's pressure is at 0c, plus a safety factor) then they know it won't ice over.

Hm.

You know you're an American when you randomly use SAE and Metric units of measure on the same system...

This thermostatic switch must be something new in AC systems since I have never seen one.

In reply to Knurled:

If that's true, it's a terrible design. Probably Calsonic.

bravenrace wrote: In reply to NJArch: That would be either a high pressure switch or a multi-function switch like a binary or trinary. How many wires are going to it?

3 Wires. If I jump 2 the compressor kicks on. Also when testing according to the factory manual it instructs me to test for for 5v coming from one of the wires, into the sensor. For the 3 wires to the sensor I think one may be a ground and the other is the wire that closes the 5v loop into and out of the sensor.

Update. I looked in the factory manual and it says that this device sends a signal to the ecu between 0 and 5 volts to control fan cooling speed. I don't know what fan they are referring to but i am not going to mess with it. Time to sweat it out. Today sucked as it was 90 and humid here in jersey. These newer cars and the complicated climate control. I must admit when it is working it works really well