Air Conditioning - AC help on contactor problem
Doityourself.com community forum was created to provide answers to all questions related to home improvement and home repair. Doityourself community can help you find information about how-to topics on small fixes to large remodeling projects. With comprehensive how-to content and expertly moderated community forums DoItYourself.com makes it easy to tackle even the most complex home improvement projects.View Full Version : AC help on contactor problem
tc861
08-04-04, 07:31 AM
I am not sure how to post this message. I wanted to ask this question in air conditioning forum but did not see anyway to post anything but a reply. In any case, problem is that when I push in contactor manually unit work. Soon as I let go, it stops. have 24 volts to time delay switch.
SHAJUL
09-07-04, 08:24 AM
This is assuming you are talking about the contactor on the outside A/C unit being depressed and your compressor kicks on along with the condensor fan when you do this.
Your problem is the coil that draws the contactor closed is failing to energize. Here are some reasons why: your contactor coil simply burnt up and opened (fixed by replacing the contactor), one of the safety/control switches opened up such as the high pressure switch or the time delay switch which causes the electrical path to the coil of your contactor to open up, voltage to coil is insufficient to get the coil to "energize" and close the contactor such as having 0-5 vac at the coil when the coil is rated to energize at 24 vac (problem is caused by a bad transformer if that is what your contactor uses as control voltage). You would need a volt-ohm meter and familiarity with electrical schematics. You would need to rely more on the electrical schematics, which is sometimes found on one the panels to your outside A/C unit, if the problem is looking more like an open safety/control switch. Check to see if there is voltage to the contactor coil by reading across the coil with a volt meter and, if there is, what is that voltage. Check and see what your contactor control/coil voltage is rated to energize at. If the voltage is correct at your coil, replace your contactor. If the voltage is low or non existent, then check to see if voltage is correct at the transformer, do this only if that is what is determined to be supplying voltage to your coil. Low or no voltage out of your transformer indicates the transformer needs to be replaced, replace transformer only after you have determined the voltage into it is good (garbage in=garbage out). Ok lets say you have no voltage to the contactor coil but you have good voltage out of the transformer that supplies your coil, then your going to need to have and understand the electrical schematics for your particular unit because your now looking for an open safety/control switch or an open/loose connection somwhere in the electrical path for your contactor coil. If you cannot make sense of the schematics or understand what I have said then your definitely going to need a professional to do the troublshooting for you.
**just read more into your post: here is some more info. and tips. You should always read across components and never to chasis ground, because you can be led astray this way especially if your transformer is not referenced to chasis ground.
Your problem is the coil that draws the contactor closed is failing to energize. Here are some reasons why: your contactor coil simply burnt up and opened (fixed by replacing the contactor), one of the safety/control switches opened up such as the high pressure switch or the time delay switch which causes the electrical path to the coil of your contactor to open up, voltage to coil is insufficient to get the coil to "energize" and close the contactor such as having 0-5 vac at the coil when the coil is rated to energize at 24 vac (problem is caused by a bad transformer if that is what your contactor uses as control voltage). You would need a volt-ohm meter and familiarity with electrical schematics. You would need to rely more on the electrical schematics, which is sometimes found on one the panels to your outside A/C unit, if the problem is looking more like an open safety/control switch. Check to see if there is voltage to the contactor coil by reading across the coil with a volt meter and, if there is, what is that voltage. Check and see what your contactor control/coil voltage is rated to energize at. If the voltage is correct at your coil, replace your contactor. If the voltage is low or non existent, then check to see if voltage is correct at the transformer, do this only if that is what is determined to be supplying voltage to your coil. Low or no voltage out of your transformer indicates the transformer needs to be replaced, replace transformer only after you have determined the voltage into it is good (garbage in=garbage out). Ok lets say you have no voltage to the contactor coil but you have good voltage out of the transformer that supplies your coil, then your going to need to have and understand the electrical schematics for your particular unit because your now looking for an open safety/control switch or an open/loose connection somwhere in the electrical path for your contactor coil. If you cannot make sense of the schematics or understand what I have said then your definitely going to need a professional to do the troublshooting for you.
**just read more into your post: here is some more info. and tips. You should always read across components and never to chasis ground, because you can be led astray this way especially if your transformer is not referenced to chasis ground.