Low pressure switch fault?
Thermostat keeps displaying error - "system in low pressure switch lockout."
Apparently this is triggered when the low pressure switch is open for more than five seconds. What would cause that condition to occur?
When the error pops up, the outdoor unit (York AC) refuses to come on. Only the blower/fan comes on. Pulling the thermostat from the wall (York Communicating Console) will cause the system to reset and it will begin operating normally again, for usually 12-24 hours. Then it trips again.
First tech said coils were frozen. Turned on fan, turned off ac. Second tech said issue was probably blocked vent or dirty filter (?!?). Company hesitant to send tech if unit is frozen. Visible inspection this morning revealed no freezing issues.
Is this something I can resolve on my own? Or is a tech necessary? System is only a few months old.
Could just be a bad low pressure switch, if you can get a tech out, he can verify this pretty easy.
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It could also be that the coil is freezing, but by the time you notice this, the system has shut off and thawed itself.
If its happening consistently every 12-24 hours it shouldn't be too difficult for a tech to diagnose.
You can check the obvious things yourself - is air filter dirty, all vents open, etc.
If the system is only a few months old, the company that installed it should step up to the plate and figure out what's going on and fix it.
Other then checking the air filter, this isn't really anything DIY. What air filter is being used?
I'm a little concerned you've had 2 techs there and still haven't been able to fix the issue.
need a better tech that will spend the time to repair it
The system came with a 100% coverage contract for the first year.
Originally Posted by Mike19
No returns or vents are blocked. I have not checked the filter to see its' condition. The thermostat has a filter change reminder built in, but it doesn't seem very reliable. It went off after just one month, which I thought was odd. I have it set for three months. I use the three month filters from Filtrete. The red allergen defense ones. But last time I picked up some of the purple healthy living ones. Was going to use one next time the filter reminder went off. Guess I am going to have to go in and check the filter myself.
The system ran fine today, no error messages or anything. I will have to ask if they checked the pressure switch. I wasn't here when they were.
Thanks to everyone for their suggestions.
Probably, turning system switch off and on will reset computer, instead of pulling thermostat.
May have an intermitant blower relay, but I would install a cheapo air filter to see if that eliminates your problem.
You need someone to come in and test the sensors. I had a Trane with similar issues, found two sensors out of spec.
They determined the low pressure switch was defective. Replaced it with a new one and system has worked flawlessly ever since.
A little peeved that the tech who mentioned the filter (same one who came back and diagnosed and then repaired the system) didn't take the time to mention the filter was filthy. There were two brand new filters just sitting there in the utility closet, he could have at least changed it out.
As for filters, I usually use the red Filtrete 3 month ones. We have multiple pets and I like to trap any dander and fur that I can.