Want to bypass pressure switch to work when i need it.

Check low side pressure or try bypassing low pressure switch with a paper clip in the connector. If pressure is good but bypass works, you need a new pressure switch. If pressure is low, charge the system. If pressure and presxure switch are good, please get back to me and I'll do some research.

most of the time you can't bypass the pressure switch because the circut board won't let you. You can however check the voltage or ohms of the switch and this will tell you if it works. On a call for heat the inducer fan starts, then the pressure switch should close contacts and send voltage through. Find common on the terminal block and put one lead on that and one lead on either side of switch and voltage should be found on both sides or remove the wires and ohm it.

If you are jumping the A/C clutch with a separate power supply there are 2 cut off switches in the system. They are used to protect the system and work with either high or low pressure.

You need to pressure test the system, idle engine speed, and bypass the low pressure cutoff to see what the readings are.

Sometimes the low pressure switch will get weak and work too early. It can be changed without losing much Freon. Put a wire loop in the harness connector after removing the harness from the switch and bypass it with the engine running. Do not let the wire loop operate withut the engine running.

There are a variety of Freon mix products to chose from. Something with a sealer and conditioner would probably be good.

As for the pressure, moderation is best. You want the compressor to run the longest for the best cooling. So a charge maintaining a pressure midway between the 2 pressure switches will work best.

If you have applied 12 volts to the system some other way, I can not imagine what was done.

The pressure switch is right next to the battery negative terminal. To bypass the switch, remove the connector and use a paperclip to jump the terminals inside the connector. By the way, you need to put oil in the system, or the seals will quickly dry out.

Hello, You need to check how much Low end pressure you have. The Low pressure cutoff switch will disconnect the compressor if the pressure is too low. The high end pressure switch will do the same thing for extreme pressure.

Sometimes the Low pressure switch will get weak and cut off the system too early. Just change this switch which will come out with only a slight puff of Freon being lost. You can jump the connector with a U shaped wire and bypass the Low pressure cutoff switch. If the compressor works better and does not cut out, it can still be low on Freon or have a bad Low pressure switch.

However, if the compressor cuts out a Second time with the Low pressure switch bypassed, the system is probably overcharged and the HIGH pressure switch is cutting off the compressor. You need to purge some Freon out of the system if High pressure is indicated.

Where it gets tricky is the Compressor will compress both Freon and Atmospheric air. Your efficency drops when the Freon is displaced by Atmospheric air. You will need to find the leak in the system which is allowing Freon to leak and outside air to enter the system. You will get a pressure reading with any gas in the lines.

There are Leak detectors and sealers for the system. I hope you just have a bad low pressure switch which is the easiest solution.

This unit must have adequate water flow and apparently needs to be checked for proper operation.

Consider the following:

The unit as manufactured is equipped with:

• pressure switch - likely stuck in the on condition, or been has been bypassed
• Thermostat - Needs to be checked to insure it is properly working and calibrated.
• Hi-limit switches - need to be checked to insure they are working and not bypassed.
• flame sensor - prevents flame from leaving the firebox and damaging control area. (if equipped)
• Flow Governor - controls water flow through the heat exchanger to prevent over pressure.
  

If the pressure switch is working properly, a blockage after the heater, would create pressure, but not enough flow. Check for a closed valve or obstruction in the plumbing.

If the problem is a clogged filter, and the filter is located before the heater, then the pressure switch is NOT working correctly and needs to be replaced or adjusted to factory settings. Remove the filter cartridge and check for flow.

Bottom line is:

No flow and no pressure, - heater should not come on.
No flow, but pressure, heater would come on and overheat, tripping hi-limit.
Good flow, heater would come on and spa would heat.

Bypassing the low pressure a/c switch can cause damage to the a/c compressor. A basic low pressure switch (two wires) can usually be bypassed by jumping the two wires. If it has more then two wires it can't be easily bypassed.

more like run a bypass on the low pressure switch

Of your system is working correctly except for the switch, it should continue to do so without the switch. However, if something fails in the system you risk sustaining more damage...just as removing a fuse from an electrical system will. One thing you did not mention is the compressor relay...have you checked that? It feeds power to high and low switches, so likely you have.

professional job do not bypass any switches as you can seize pump up,its not working because the gas has leaked.end of story