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Have raypac spa pro electric heater. set thermostat to start turn on timer heater contacts pull in heat starts then contactors fall of line. flow through pump is good,

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The high temperature limit may be shutting off the heaters when they registera high temperature conditiojn that is dangerout. Have you gotten to run the heater long ehough to take a temeperature reading betweeen the supply and the return? also do you have strainer in line with the piping to the boiler.and is there a pressure switch for if the unit develops too much pressure. And how can you tell how many gpm your moving thru the boiler? these are the thing that a compenent service technician can check out and correct the prolem. exspecially since this is a boiler and if its improperly repaired it can explode and do lots of damage..that being said I strongly reccommend that you call a service company to service your boiler. THaanks for using Fixya

Posted on Dec 24, 2008

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Posted on Jan 02, 2017

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Split system is not heating however the fan outdoor is ok and the unit inside is flowing

If everything seems to be working but it's not heating or cooling, check the contactor that turns the compressor on at the outdoor unit. Make sure you have power through both legs of the contactor because sometimes they will build up carbon an the contacts and not allow normal electrical flow. If the contactor is pulling in and there is power going through it, you'll need to check the run capacitor and the compressor itself

Aug 16, 2016 | Electrolux Heating & Cooling


What to check when you air conditioner will not stop running:

If you discover that your outdoor air conditioner and/or heat pump runs continuously even with your thermostat off and the indoor blower is off, the most probable cause is a stuck contactor. In most residential air conditioners / heat pumps, the contactor is the switch that allows voltage to your compressor and condensor fan motor; therefore, allowing them to run. The contactor allows line voltage (normally 208 - 240 volts) to pass through a set a contacts to your motor. The contacts pull in when the thermostat calls for Cooling and they "open" when the thermostat "satisfies". This is accomplished with the use of a low voltage coil. When 24 volts is applied to the coil, it creates a magnetic force that pulls the contactor in to close the contacts. When the 24 volts is removed from the coil, the magnetic force no longer exists.....a spring will force the contacts back "open" and stop the compressor and fan motor from running.
The contactor is considered a wear-n-tear item as, eventually, the contacts will wear and begin to "pit". Eventually, they will either pit so severely, they will not allow enough voltage through them to operate the motors OR they may allow enough voltage and then overheat and weld themselves together. Often times you can lightly tap on the contactor and it will "free" the contacts and stop the motors. Unfortunately, once the contactor starts "sticking" it is highly likely it will stick again. Therefore, it is recommended that the contactor be replaced at first sign of sticking or when the contacts show signs of damage/overheating via a visual inspection.

Here's a video that might be helpful to you. :-)

on Apr 27, 2010 | Heating & Cooling

1 Answer

I have a rudd UHLA-3617JA high achiever air handeler, works fine except the electric heater will not come fan starts normally, is this a fuse/breaker or failed electric element problem, how can i tell

It is either the element, sequencer (or contactor/relay), or power to the switching element. 5KW Elements normally Ohm out @ around 10 Ohms when they are good. Everything you need to check requires a multimeter.

Jan 21, 2015 | Heating & Cooling

1 Answer

Outside AC unit not coming on but indoor fan is working, replaced the start/run 5/50 capacitor but still didnt fix it, let it set allday while came home tried it and it came on and worked great, but the...

Sounds like you are on the right track. The symptom of the contactor not pulling is your clue to the solution. When you turn the thermostat down lower than the room temperature and the thermostat calls for cooling, the outside unit should start immediately. There are a few exceptions to this but generally this is correct. So if you turn the system to cool and the thermostat is calling for cool then the contactor should pull in immediately. If it does not then check for 24 volts to the contactor. If you have 24 volts to the contactor then the contactor is the problem. If you do not have 24 volt power to the contactor coil then you will have to find where the break in voltage to the contactor is happening.
There are many reasons why you may not be getting 24 volts to the contactor, so check what i stated above before you go any further. Repost if this is the solution or you need further assistance.
Important tip....the yellow wire from the thermostat carries the 24 volt power from the thermostat to the contactor.

Sep 08, 2011 | Intertherm P3RA-036K Air Conditioner

1 Answer

I have a Fredrich 8000btu wall unit model number CPO8F10 and the compressor will not shut off, even when the unit is turned off the compressor keeps running. the only way to shut it off is to unplug...

If your air conditioner or heat pump compressor won't shut off unless you pull the fuses or turn off the circuit breaker. You probably have a stuck contactor. The contactor is the name we give to the big relay that controls your air conditioner, heat pump or other large electrical device. If the indoor blower fan will not shut off either then the problem is NOT the contactor in the outdoor unit but a problem with the thermostat or the wiring to it either at the subbase or the furnace. Before replacing your thermostat you should isolate the cause of the problem or it will persist and drive you nuts. Look for wires touching or cut too long. A contactor or relay is an electrical device that takes a control signal usually 12 volts DC, 24, 120, 208-230 volts ac and creates a magnetic field to pull in a set of contacts that controls another device that may or may not get its electrical power from the same circuit. Note: 99% of most control circuits are 24 volts AC. The contactor has steel contacts that are plated with silver. When the silver wears away you have just plain steel and the steel will weld itself together. Sometimes if you whack the contactor with a screw driver you may free it for a while but the problem will re occur. This problem is especially a problem when a piece of equipment has not been run for a period of time. It is normal for the contactor to wear out over time like brake pads on a car. If the contactor shows any signs of wear it should be replaced as a preventative measure or as part of maintenance. If you suspect a stuck contactor a 100% accurate test is to turn off the power to the indoor section which removes control voltage to the outdoor section and it (outdoor section) keeps running. Do not keep messing with it, your contactor it is bad and you will destroy your compressor if you let it run!!! You can also have problems with spiders building nests in the contactor; the silk is an insulator and will prevent electricity from flowing. Replacing a contactor is a simple matter and they are readily available. Costs vary from about $40 installed to several hundred dollars depending on the size and current carrying capacity. If your compressor does not shut off when it needs to and the indoor fan does you will destroy your compressor. The high and low pressure cut-outs won't work either.

Aug 20, 2011 | Friedrich Heating & Cooling

1 Answer

My contactor will not pull in

If the contactor won't pull in the first thing to check is the low voltage circuit to the contactor. Is there 24v going to the contactor? If yes and the contactor is not pulling in, then you have a bad or dirty contactor. I have often time seen bugs get in between the contacts and stop the flow of electricity. If there is not 24v being supplied to the contactor then you will have to check your thermostat and the wiring from the furnace to the outdoor unit. Hope this helps

Aug 14, 2011 | Goodman Heating & Cooling

1 Answer

Outside will not come on

First check the circuit breaker or fuses. Remove the cover on the outside unit that covers the contactor, circuit board, and capacitor. Check for voltage on the line side of the contactor. Set the thermostat to make the air come on then check the contactor to see if it is pulled in (contacts closed). If it isn't pulled in then check for 24 vac on the contactor coil. If the contactor is pulled in check for voltage on the load side of the contactor. If you have it there then check the capacitor(s). Some units have 1 that runs the fan and compressor and some units have 2 ( 1 for the fan and 1 for the compressor). If you don't have 24vac at the contactor you can install a jumper at the thermostat between R and G if it is just an air conditioner or R and Y if it is a heat pump and see if the thermostat is bad.

Aug 13, 2010 | Goodman CKL42AR42 Air Conditioner

2 Answers


The outside fan may run if the unit is in defrost mode this is normal for most heat pumps it is there way of trying to keep the outside unit from staying iced over so the next time the unit runs it will have air flow through the coil and the ice will not be there to prevent air flow.

Jan 12, 2010 | Carrier 38CKC042 Air Conditioner

1 Answer

A/C unit will not shut off

pls the connection of the thermostat is
Y - COOL (compressr contactor)
W- HEAT ( heater contactor)
after you check the voltage 24 v between r and c slect cool then set thermostat at low temp the fan will start after the compressor will start

Apr 27, 2009 | Heating & Cooling

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