This house needs new ductwork. The air is blowing under the house. Beign replaced tomorrow. The tenants are super clean freaks. They purchased the vent filters and put them over each vent. Air flows out Can fill it when you rub hand across vents.. Since then, the AC shuts off. It's not the capacitor, the coils have been cleaned, the condensor is good. I was wondering if the inside filters one each vent is causing the unit to short circuit some how?

Any idea why while i go in search for a window unit? Thanks

Not an a/c expert here but common sense says:

*Putting filters(blockage) over each vent causes the unit to work harder to move a given volume of air, thus causing extra wear and premature damage and failure.

*Because there is not enough volume of air flow, the cooling ability of what air does come through is less.

* The tenant, now not being cool enough, turns the unit even lower, causing even more of the same.

*overworked unit fails. Just like a heater when the filter gets clogged.

*The damage to your unit is the fault of the tenant. Their use of filters which block the airflow has caused this. They should pay for repairs.

*they are going to deny this and attempt not to pay for damages they caused.

*I'll bet you can verify this just by removing these filters and restoring airflow to normal.

If the blower does not move enough air across the evaporator coil, it gets too cold. The condensate then freezes on the coil and blocks all air flow. At this point you won't get ANY cooling until the ice on the evaporator coils melts down again.

I rehabbed one of my units and here's a similar story....

1962 unit, 1100 sqft. Had brand new full HVAC system installed...ducts/AC/gas furnace. All worked fine when tested.

1st tenant lives there 1 year, all works fine.

2nd tenant moves in, all works fine for 2 months. Month 3 I get a call that the unit is cycling frequently (runs for 5 minutes, shuts down for 15 minutes, repeats).

I go to the house, notice he has a NEST thermostat...he said he's an environmental policy person and likes to save energy. I ask him to remove the thermostat and replace with the old one to see if it fixes...we do that and wait one day....problem still exists.

So I go back over. Check filter (I personally go to all rentals about every 6 weeks and change filters, so I was pretty sure it was not all clogged up...but I checked anyway). Filter was clean, but was a different brand than I used. I asked him about it and he said his wife has allergies so they took out my filter and installed an allergen filter with a hi MERV rating. I told him this may be creating excessive backpressure. I changed it back to the basic filter and checked on him 3 days later...problem solved.

Most people don't realize that when the furnace motor is sucking in the air-- that air cools the blower motor before it crosses the coils. So if you restrict the air it can't cool the blower motor. The answer to your next question-- why does it come on a while and go off? -- the motor has a thermal trip device built into the motor to keep it from burning up when it gets toooo hot. So the motor will work until it overheats-- shuts off and when it cools the motor comes back on.

I really wish they would quit selling those allergen filters. I go over this at lease signing to use the basic $1 fiberglass filters or it will create a problem. I even leave a couple of extras for them.