I have a Carrier AC 38ed030310 its been working well up to yesterday... Now I have found that it just would not start up .... so opened up the unit to see what it could be .... only to find if I push the relay contact unit the fan and condenser startup . so at that point the AC was working ... but a bit manual .... so there looks to be a problem with the startup .. what should I look to replace?
Thanks
Either the relay is not getting 24V from the T-stat or the relay is defective.
You need to do some troubleshooting, and find out why the relay isn't pushing in automatically. That could be any of a bunch of reasons. A HVAC service tech should be able to diagnose that and have it fixed, in an hour or so.
It can be several things all of which are just a guess from behind this screen. Get a price on a new unit then decide exactly how much you want to risk destroying the current unit you have. Id suggest a professional if you dont exactly know what you are confronting. Bubba
I believe some of the newer condenser units have a switch in line with the thermostat that is controlled by the freon pressure to make sure the compressor does not run when too low. I would take some measurements before I held in the contactor for an extended time.
That long? Gee. It would take 5-10 minutes but it would still be a minimum of an hour charge. Using a quick charge device makes installing the freon less time consuming if it's low on freon. There are times when the condenser is plugged up from pet hair or some idiot mowing the lawn in front of the condenser when the AC is running and that would take an hour to properly clean the darn thing especially if there is six inches of compost surrounding the compressor. If it's a quality unit it will have a high pressure cut out with a red rubber manual reset button and someone already mentioned an automatic low pressure cut out. One of the most common problems that will keep an AC from running is a loose blower door on the air handler/furnace. Of course that will keep the blower from running too. The original poster didn't mention if the air handler was running or not. Your basic non heat pump AC without bizarre electronic controls is so simple it only takes a few minutes to figure out why it's not running.
[8~{} Uncle Monster
It's just a regular AC unit ... not a heat pump... the blower unit in the house is working normal... the system was recharged last year it had not really lost much .. so the engineer told me..
I have been running over night with the contact pressed ... so as the AC is on ... and has worked all night and really well .... I am still thinking its a starter issue kinda thinking its a relay or capacitor issue... what you guys think ??
The capacitor is probably a dual type with three separate insulated terminal posts marked "C", "F" and "H". The letters stand for Common, Fan and Hermetic. The term hermetic means compressor since the compressor is the welded can hermetically sealed variety. It can be confusing since the bolted together compressors are known as semi-hermetic. If the capacitor is bad, neither the compressor nor the fan would run. If the contactor is not pulling in, it could be something as simple as a break in the low voltage circuit going to the condensing unit. A loose wire nut on one of the two little wires would keep it from running. The wires can be twisted together but one of then could be broken off under the wire nut. Or the control wire coming from the house could have been damaged by a weed whacker. The last thing could be a defective contactor if there is
24 volts ac coming from the air handler via the thermostat. I have found that most of the time, it's something quite simple. [8~{} Uncle Monster
Replace your logic, you have no idea and have not tested anything to see what failed, you dont just take medicine if you dont know what ails you, do you, well maybe you do.
Most likely NOT a starter or capacitor issue. A bad starter or capacitor won't stop the relay from closing. Your problem is the honkin' relay!
Either the relay's not getting 24v to energize it or the relay itself is shot.
You can eliminate the 24v possibility by measuring the voltage on the relay when it's supposed to be energized. No voltage? Then the thermostat is shot or the transformer supplying power to the thermostat has gone bad (or a wire has come loose).
24V present? Then the relay is fried. Replace it.HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.