I keep getting a feeling that your “piece of equipment” is only a low side gauge that lets you charge a system from a can only!

That gauge will not work correctly or in a sense of accuracy, on a 92 system. The 85 has a sight glass for filling and the 92 requires a weighed out charge as it does not use an expansion valve.
The 85 can tolerate a slight overcharge but the 92 has to have a precise balanced of liquid held on both sides of the expansion device, called an orifice, during its proper operation.

Both systems have an over pressure valve or overcharge safety valve and you do not want it to pop off, as it will create quite a mess from compressor oil. I have a point to make, I think...

To save time, I will suggest as others have, that if you do have enough liquid on the low side. That said the low side switch (located on the aluminum can by the firewall) does present a greater propensity to go out of adjustment or out right fail.

It is replaceable without discharging the system. There is an adjustment found in between the connector prongs but if the switch has lost its preset temperature/pressure differential, the switch is finished.

Only caveat is you do not know what both sides of the system are doing and it is crucial on the 92 as one switch could be saying it is low or the high side switch, is saying I am way to hot or too a high pressure, shut down or turn on a fan!

You really should be using a “refrigeration gauge set”. For charging you also need a “weight scale” graduated in ounces i.e. a postal scale, as “pieces of equipment”.

Yes, you can use a jumper wire in the connectors. You have to be careful not to pull the compressor into a vacuum for an extended time by over riding the low side switch. Reason is, if you have a leak on the low side, you just pulled in air that has moisture! The other bad news item as it can freeze up the expansion devices. The symptom becomes intermittent cooling.

You might have something else going on besides a charge problem.
Let us say you jump out a high side switch and you have a dirty orifice, all the refrigerant, an excess or not, can end up on one side and poof, you have some oily fog under the hood! Be careful or you might not be the only thing on the jump! (:)

How well was the A/C cooling before you dived under the hood?

Phil

I have a '93, which may or may not have a different set of sensors (I know the refridgerant is different unless you upgraded at some time in the past), but I would at least check the sensors' role in the rapid cycling by (one at a time) disconnecting the electrical connectors (plugs) to the sensors. This would eliminate the signal (open or closed circuit) through the sensor -- and maybe the system would work normally.

If, for example, the system then works correctly, you'll know that it's the signal from the sensor that is responsible for the problem. But you still have to determine whether it's a false or true signal.