Ac Checks in March

[powderedtoastman]

I don't trust it at all, but my company has us do it. Certain customers want us out once a year for the furnace AND the a/c maintenance for whatever reason. We check refrigerant charges in January. Frankly it's a sick joke to me. Just a method to say, "yeah, we did your maintenance." Unless it's a heat pump, reschedule for May at least... You have to run their furnace for half an hour to get the indoor temp up to at least 75, then hope the indoor air isn't to humid. No, you're not the only one.

[Kevin Weaver]

I have done hundreds of a/c tune-ups in cool to cold weather. I remember a few where I washed outdoor coils standing in snow. The only thing about blankets, cardboard garbage can lids is that you are simulating hot weather, but what simulation temperature are you simulating? 80-90-110??? And then there is no load inside. Don't add refrigerant! do your thing, clean drains, coils, filters....... and just hope charge is good. Company's do it to keep tech's busy and try to avoid the big rush the first days its hot out.

[EugeneTheJeep]

In my area, going to be cold the rest of March and into the beginning of April. At least we can get going on the commercial PMs. But them homes are usually in the 60s in early spring and the same out doors. But even on days like that you can tell if a system is low on refrigerant or not, but it will not be accurate.

[bmac]

We made up a control to adjust the condenser fan speed to whatever head pressure we want. Seems to work well. We will come back when warmer if we see a problem or need a recharge etc.

[hurtinhvac]

We made up a control to adjust the condenser fan speed to whatever head pressure we want. Seems to work well. We will come back when warmer if we see a problem or need a recharge etc.

More detail concerning this control, please...

[bmac]

4 x 4 box with a toggle switch and a rotary speed control switch, like for a ceiling fan. Two wires with spade connectors to hook in series with the condenser fan motor. Adjust the dial to get the head pressure where you want it.

[mason]

4 x 4 box with a toggle switch and a rotary speed control switch, like for a ceiling fan. Two wires with spade connectors to hook in series with the condenser fan motor. Adjust the dial to get the head pressure where you want it.

So it's the power thief version of the ICM head pressure controls : ). Just don't dial down a sleeve bearing motor too far or it's bye bye.

I still have a question, this will work on a txv system as you get the head pressure up to a "normal range" and assuming a decent load on the evap coil can confirm subcool and check that the txv is delivering superheat bbuuutttt.... It still doesn't work on fixed orifice if you want to do it right : / and that's still a lot of units. You need an actual measured outdoor temp with your indoor WB, unless I'm missing some crazy awesome superheat chart based off forced head pressure, very possible.

[bmac]

We're not charging the units, just making sure they're in the ball park, on a maintenance check. We try to simulate the pressure of a 95 degree day. Old units might be 125 sat. temp, newer will be lower, depending on efficiency. Again, if something doesn't look right or charge needs adjusted, we put on a list to return when warmer.

If we didn't do it this way, we couldn't get them all done in our relatively short summers.

[mason]

We're not charging the units, just making sure they're in the ball park, on a maintenance check. We try to simulate the pressure of a 95 degree day. Old units might be 125 sat. temp, newer will be lower, depending on efficiency. Again, if something doesn't look right or charge needs adjusted, we put on a list to return when warmer.

If we didn't do it this way, we couldn't get them all done in our relatively short summers.

That makes sense.

[EugeneTheJeep]

15 Degrees out this morning, I do not see March PMs happening here?

[motoguy128]

Set up a tent. Run the condenser in the tent until the ambient air (in the tent) is at the desired temperature. Then, perform your checks. It adds a bit of set up time, but will more accurately simulate a 90 degree day.

I like this one. Leave it to someone in MN, to come up with a better solution. Probably since a 85F day only happens for about 6-8 weeks in late afternoon from July and August up there.