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Low Pressure Cut Out (LPCO) Fault - Heating & Cooling

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Why my heat pump only heat in emergency heat only,the condens is cutting off and on

It sounds like a maintenance issue with your heat pump, its clear that the unit is trying to run but one of the safeties is shutting it down trying to protect itself. most heat pumps are equipt with a High press lockout usually a manual reset ,a low press, cut out switch resets on rise of press automatically. Causes of LPCO Extremely dirty condenser coil or evaporator coil, Loss of fan on condenser, Low refrigerant charge. A competent Service man should be able to locate and correct this problem. A seasonal check up on the unit avoids these problems.

Feb 22, 2015 | GE Zoneline AZ38H12DAD Split System Air...

1 Answer

My compressor will not cut out when up to pressure what can the fault be?

You have a pressure regulator somewhere on the unit that is adjustable for low pressure kick in and high pressure cutout. Turn the high side out after pressure is where you want it to cut off and it will do so. Low pressure cut in should stay where it is.

Nov 29, 2014 | Stanley Air Tools & Compressors

1 Answer

The a/c in my 02 Silverado doesn't blow cold air. The compressor comes on for 2 seconds and then off for 8 seconds, and continually repeats this pattern. What are the possible solutions?

The symptom is likely that of a low refrigerant charge. The LPCO cuts off the power to the clutch when the Low Pressure in the evaporator is reached. Prevents frosting the evaporator and starving the compressor of refrigerant/lubricant mix. Check pressures, look for the leak, repair, evacuate, and recharge. After 12 years, it might be a good idea to replace the dessiccant carried in the accumulator or receiver/dryer if you have to open the system for repair. Look for 'oily/dirty' spots where the leak carried some oil out and trapped some dirt.

Jul 23, 2014 | 2002 Chevrolet Silverado 1500

1 Answer

Where is the ac relay located on a 1994 ram van 3500?

It maybe a low gas pressure fault as low pressure will not allow compressor to drive.

May 26, 2014 | 1994 Dodge B Series Cargo

1 Answer

My low pressure fuel pump on my e270cdi cut out under high load pressure from the rear.all fault codes tell me the rail pressure is to low

Fuel pump relay is in cavity A in the rear SAM ( Signal Acquisition Module.) on the left hand side of the trunk behind a door.

When did you check the voltage..... you must read it while cranking or you will get a zero voltage reading.. The low pressure tank pump builds pressure to the high pressure pump and then shuts down until a pressure drop is sensed in the low pressure line and it then starts up again.

If rail pressure is too low, it often is the high pressure pump in the engine or the relief valve in the fuel rail. The tank pump is low pressure just to stop the tandem pump from cavitating by sucking too hard.

Mercedes can check the rail pressure and do an injector pressure drop to rule out a leaking injector.

If the tank pump is bad it will require replacement.

Oct 20, 2013 | Mercedes-Benz Cars & Trucks

1 Answer

My ac is blowing hot air. I've checked the gas and it's full. The compressor seems to cut on and off about every 10-15 sec. Do I need a new compressor or do I have some sort of fault switch? Any...

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.

Jun 25, 2011 | Ford F-150 Cars & Trucks

2 Answers

1993 VW golf 1.8. oil is leaking from oil pressure sending unit, i've replaced the unit but now the low oil warning buzzer is going off (didn't previously do this) and warning light stays (also not a...

It seems the fault is with the oil pressure switch you have replaced. This switch seems to need a higher pressure to cut off and the oil pressure light is coming on because it indicates low.
So if your oil is good , the oil filters were changed recently this fault must not come up. if not replace oil and oil filters to check but keep this option that the fault was never there earlier and a new part can also be faulty.

Sep 24, 2010 | 1993 Volkswagen Golf

1 Answer

When I put paper clip ac works but Otherwise it ...

The low pressure switch on the a/c line is at fault or you have to little freon in system to make the pressure switch work. The low pressure switch is put in the a/c line to keep you from burning up the a/c compressor. Anytime the freon fall below a certain level (pressure) then the switch will cut out to keep anything from burning up. Hope this will help you.

May 20, 2010 | Cars & Trucks

2 Answers

No voltage to a/c clutch, freon pressure fuse and TCM module check OK , where is freon low pressure cut-off switch located ; 1999 chrysler LHS

put it on a special machine to weigh the amount of gas in the system by extracting it ,then refill to the correct weight of gas ,if still not working then work backwards looking for the feed and try to isolate the problem ,like the AC on switch and then the blower motor switch

Apr 03, 2010 | 1999 Chrysler LHS

3 Answers

A C works intermittantly

As far as the heater damper goes, you will definitely have to get taken care of. Not sure if they are vaccum or cable type on that year. I am going to say that you need your ac recharged. If it is low the compressor will kick in and out. Another possibility is the control panel where the controls are. Good luck

Jul 24, 2009 | 1995 Ford F250

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