a/c unit

[SgtMaj]

Well, since last year my a/c unit has been freezing up occasionally... this year it's noticably worse than usual. By freezing up I mean the return line (the large one) freezes solid and doesn't return the coolant, or so I presume, since the air coming out of the vents isn't cool when it does that. Anyway, last year we just turned it off for 15 minutes and then back on again and it was enough to temporarily "fix" the issue. This year it's been getting annoying doing that every day twice a day and the house get's HOT, like 80 degrees hot while waiting on restarting it... and it's not even all that hot outside yet, summer has just begun. Anyway, been fighting paying a pro to come out and fix it since I know it'll be at least a couple hundred bucks. I researched the problem and found that the most likely cause is a slow freon leak. Being the "smart" guy that you all have come to know me as... ...I figured that the unit couldn't use R12 since the house was build several years after R12 was banned. So being the "genius" that I am... ...I figured it most likely used R134a, just like vehicles do, since if that's the best freon for vehicle A/C's, then it must also be the best for home A/C units... so then I figured that being the "brilliant" guy that I am... ...I would just recharge it myself using the car recharge stuff which I use frequently on the jeep because it also has a leak and requires monthly recharges in order to stay cool in the summer, and I would just save the service call on the home a/c unit. Turns out... big surprise for you all I'm sure... ...that it has a slightly different connector than the vehicle A/C's have. So the net result was a slight further loss of freon from the home a/c unit which makes the problem even worse. I'm sure you're all shocked that I would do such a thing... ...so anyway, I figured I'd just go out and buy the right connectors to charge it and still save the service call. But it turns out that around here you apparantly have to be a liscensed HVAC person to get those connectors. DANG it! Now I'm going to have to hire someone to come out and refil it... and I'm sure they'll want to try to find and fix the leak... all of which will cost money I'm sure. Why the state won't give me of all people... ...a liscense just because I'm me, is beyond me. Surely they've heard of my other projects and can see I'm obviously qualified... lol (unable to use image again because I'm limited to posting 6 images per post).

In my defense, I have successfully fixed this a/c unit before... when the capacitor died a few years ago, I was able to successfuly diagnose and repair the problem myself, and thankfully I was able to buy a capacitor for it without being liscensed.

I realize I would only be "renting" the freon since I don't have the know-how or parts to fix the leak, but since R134a poses no serious environmental concerns, I still think I should be able to refil it myself. I don't think that spending $200+ to get it fixed right is better than spending $10 every 3 years to refil it myself.

 

[JCF350]

Re: a/c unit

Older home A/C units used R-22 and used the same connectors as the automotive R-12. Might have to do some scrounging, for the connectors. R-12 is still available (license required) for use on auto A/C units.

Might could find an old set of gauges and use a side tap for the can.

 

[dimock44]

Re: a/c unit

OK Sarge, first find the name plate and verify what freon it takes, also what year it was manufactured. Could be R22. You really need to get it fixed because some of the old piston compressors fail from overheating when they are short of freon. Also it will run continuously and wast a lot of Killywiggles. Be sure and get a service tech to come when you are there. and stay with him and get him to explain what he is doing. The rule used to be they are required to fix the leak if it loses 50% of the charge per year. But I've been retired several years so it might of changed. The total Freon charge should be on the name plate also. Get me a Model # and I might remember something If its one of the brands I use to sell. Look for oil on the piping or unit that would indicate a leak. Good luck

 

[TilliamWe]

Re: a/c unit

And if you don't find a leak, clean everything real good. Take the cover off the unit and spray water through the condenser. Then if the evaporator is in your furnace inside, make sure it doesn't have dirt plugging it. ( I carefully vacuum mine with my Shop Vac with the soft bristled attachment) My 31 yr old A/C unit would stop cooling and the one line got ice all over it 2 summers ago. I called the same company that did some nice honest work on my 31 yr old electric furnace, and he checked the refrigerant (good, no leak) and cleaned it all out with my garden hose and it worked. Charged me $75 - one hour. Then told me to keep it clean and I have and it works. Good luck to you.

 

[guy74]

Re: a/c unit

What makes you think it is low on refrigerant? Home a/c's generally use R22 refrigerant, can't get it without a licence. Most of the time when the low pressure line get a coating of ice it's because of a lack of air flow though the evaporator. I would bet your evaporator is plugged up with dirt and lint, then it freezes up causing the cooling to stop. I use a special foaming spray cleaner, and compressed air to clean the evaporators on A/C units I work on.

 

[SS MAYFLOAT]

Re: a/c unit

What makes you think it is low on refrigerant? Home a/c's generally use R22 refrigerant, can't get it without a licence. Most of the time when the low pressure line get a coating of ice it's because of a lack of air flow though the evaporator. I would bet your evaporator is plugged up with dirt and lint, then it freezes up causing the cooling to stop. I use a special foaming spray cleaner, and compressed air to clean the evaporators on A/C units I work on.

Exactly. DO NOT PUT R134a into it. Most older units use a mineral base oil. R134a has POE oil. Not compatable at all. As mentioned above, decreased air flow is the common problem. As the airflow over the evap coil decreases, the suction pressure decreases and causes the evap to go below freezing temp causing the condensate to freeze blocking the airflow even more. Just because the fins look clear, does not mean that there is dust/lint stuck inbetween them. Like also mentioned, it uses R22. The spec place should also tell what the weighed amount should be for the system.

Also, pull out your evap blower. It should be a squirrel cage type. If the blades/vanes have a build up of dirt, that itself will reduce your airflow substantially. The fittings are known as 1/4" schrader. Just one of the reasons to prevent DIYers in doing jobs that should be done by trained pros.

Also, clean the condenser coils. This area is where a lot of efficiency is lost and prevents compressor burnout.

 

[TilliamWe]

Re: a/c unit

I knew Willie at G&B Heating and Cooling in Peoria wasn't yanking my chain when he told me to clean it out and it would be fine. SS and guy second and thirded his recommendation. And I have done what he said for two years with great results.

 

[JCF350]

Re: a/c unit

Exactly. DO NOT PUT R134a into it. Most older units use a mineral base oil. R134a has POE oil. Not compatable at all.

R134a does not have oil unless you buy it with oil in it. The similarity in working pressures make it a decent substitute for adding to home A/C units.

BTW your thinking of PAG oils. POE oils are used for R-12 to R134a conversions because they are compatible.

 

[SgtMaj]

Re: a/c unit

So what you all are saying is that it doesn't really matter now that I've let some of the freon out, I'll have to hire someone to replace it, and in the future, I should be smarter about it and just check the condenser, etc for dirt... which is pretty much what I had already concluded by the end of my first post, right?

 

[SS MAYFLOAT]

Re: a/c unit

R134a does not have oil unless you buy it with oil in it. The similarity in working pressures make it a decent substitute for adding to home A/C units.

BTW your thinking of PAG oils. POE oils are used for R-12 to R134a conversions because they are compatible.

My bad,,,,I was told that 134a is not compatable with mineral based oil. Guess that is what I should have said. I use a lot of 404 with POE. Getting to be too many different gases available to keep up anymore. I've pretty much gone with Hot Shot for all of our small appliances. Seems to hold up without many failures. Thanks JCF for the heads up!.......SS

 

[JCF350]

Re: a/c unit

My bad,,,,I was told that 134a is not compatable with mineral based oil.

Before I sold the shop this was all you would have heard from me also. However nowadays I can.......

 

[Benny1963]

Re: a/c unit

hi sarge you may want to put some gauges on it ,
its probaly low .its also probaly r22 and its not r12
havent seen many 134a conversions in houses yet
if its low it probaly has a leak since ac units do not use up freon
but they will leak it. the large line is the suction line
the small is the high side some times a faulty drier will cause a freeze up
you would need to put gauges on it and read the high and low side
depending on the climate you will get different readings
if you read the out side line on your gauge you will be in the area of 65 lbs
os suction and well below three hundred on head pressure
if the small line is hot check evap coil .

 

[NW Redneck]

Re: a/c unit

Could be:
Low charge
Restriction in the lines
Blocked/dirty piston oriface/txv valve
Faulty/stuck piston/txv
Non-condensibles in the lines
Dirty filter drier
Worn/failing compressor
Dirty evaporator blower
Worn bearings on evap blower/motor
Dirty/obstructed evap coil
Restriction in the ductwork

Running it undercharged/overcharged/dirty will drasticaly shorten the life of the equipment and be $$$ out the window in increased operating costs. Just call a pro to check out your system. How old is it? How well (if at all) has it been serviced/maintained? You may be at the point where it will start to break more and more often and may be time to consider replacement. If it is 12+ yrs old, seriously think of replacement. Newer equipment is much more efficient and often quieter.

I didn't stay at a Holiday Inn last night, but I am an HVAC tech.

 

[thefairlaneman]

Re: a/c unit

If the outside coils are becoming covered in frost this means the automatic defrost timer isnt working.Mine did that and the only way to defrost it was to turn on the ac which would blow warm air out for a couple of minutes and melt it. then back to heat for several hours and repeat,,defrost switch you can install yourself and save several hundred. TURN OFF POWER FIRST