View Full Version : Any HVAC Guru's Here?

Aug. 9, 2010, 07:10 PM
I just spent $500 on my central air unit because it was running constantly and on auxillary (the little green lite stays on) plus the air blowing through the vents was warmish. He changed a part (definite purpose contactor 1 pole ?) because he said the ants got to it and then told me I had to spend another $150 to change out the thermostate (digital) because the old thermostate was making the unit run continually. He also told me I need freon but I can only afford so much in one day.

Well, the guy left over 5 hours ago and the unit is still running constantly---set at 75 to cool in the auto position. Even after changing the thermostate. I have put in three calls and each time I am told that because it is over 85 degrees outside the unit will run constantly.

Is this true or am I being handed a load of bull hockey? I am wondering if I should put a stop order on that check until they fix this thing.

PS. The unit just shut off and after 4 minutes came back on. So the unit is running for over an hour and shuts off for 4 minutes and then comes back on for one hour. Will the temp outside cause this?

thanks for any and all replies.

Aug. 9, 2010, 09:15 PM
My DH (an engineer who designs HVAC systems) said that if this is atypical for your unit, then it's entirely possible that you also need freon. He asked if your unit functioned fine without continuously running last year in August when it was this hot. If it did not, then you could need freon. He feels like the repair guy is sort of "guessing" at what is causing the problem by changing the relay (pole) and the thermostat... but they are educated guesses and good places to look when you have this problem. He said it does sound like the tech was trying to troubleshoot, but without more info, he can't say if it was appropriate or not. It doesn't sound from what you wrote that he did anything wrong or is trying to rip you off. It is possible that he maybe wasn't efficient with your time and money by guessing - but he also may have had more info than you posted (or than you are aware).

If this is typical for the unit to run continuously when the temps are over 85 (i.e., it did this in previous years when temps were this high), then it is possible your unit wasn't designed to handle these higher temps. That means running continuously is normal for the unit when the temps are higher. My DH said that most units (at least in our area) are designed to keep up and run pretty efficiently up to about 95 degrees, though. In fairness, he works with larger commercial units for high rise buildings -- but he said that the residential units are designed for about 95 degrees in our area, too. In our recent heat waves where the temps have been well over 95, our CAC has been struggling to keep up, but it runs pretty efficiently at 85.

Good luck - I hope you get it all straightened out!

Aug. 9, 2010, 09:30 PM

Thanks so much and tell hubby he's the best for taking time to assist me. Yes, the serviceman did say it needs freon although it is blowing nice cold air in here. I will have to have the freon put in but it will have to be later.

I have been timing the unit and it is cycling on 15 mins and cycling off for 8 mins.
So, this is much better than it was earlier as it was cycling on for 47 mins and cycling off for 4 mins.

I guess as it cools off in the evening the unit does not have to work so hard as when in the daytime with temps in the upper 90's. The heat index has been really high lately so maybe that's wht the unit is staying on for the most part. Gotta love the Carolinas.

Thanks again and give that hubby a hug from me.

Halt At X
Aug. 9, 2010, 10:02 PM
If you are low on gas your unit will not be able to or take a very long time to cool down the house after being off in the hot weather. 85 outside means it's much warmer in your house, particularly upstairs if you have a second floor.

Residential HVAC guys are professional parts changers. They'll just keep changing parts until it works. Did he even put gauges on it?

Our ac has been running constantly, but it's been consistently in the 90s here and humid- the ac will run to cut down the humidity in your house as well as cool it down. If you do have a second floor I highly recommend putting in an averaging sensor. It is a small piece that you put in the warmest room upstairs (we chose our room since the dog sleeps in there and the 3 of us create a lot more heat than either kid does in their rooms) and the thermostat will average the temps between the floors so you don't get that obvious, "wow it's a lot warmer upstairs than down" feeling.

My husband works in heavy commercial/industrial HVAC and he sees people get ripped off by residential guys all the time.

Aug. 9, 2010, 10:50 PM
Thanks Halt@X:

No, I only have one level but it has been terribly hot here--think hades. LOL!

I have to agree that this guy was a little fast and loose with the parts but I really did need to have the thermostate changed. Only now I find out I probably could have done that myself for about $30 from Home Depot.

One of the girls on here has a hvac company and if I have any other problems I'll definitly call her. She is very honest and wished I had remembered her earlier.

Live and learn.

Aug. 10, 2010, 01:17 AM
Being low on Freon will cause the a/c unit to run more because the shortage reduces the cooling capacity. Plus, when it is very hot outside, more heat is gained by the house.

All these add up to make your a/c unit run longer and use more electricity.

If you needed more freon, your system has a leak. Each year the leak will get worse, until someone finds and repairs the leak. Depending on the unit's condition, it might develope another leak too.

Aug. 10, 2010, 06:47 AM
Thanks hosspuller:

I relly do not understand anything about hvac but I can replace an alternator in my truck LOL!

I will definitly keep in mind about the freon and a leak when I call out Fudgie's serviceman to check this unit. Thanks

Aug. 10, 2010, 10:03 AM
Residential HVAC guys are professional parts changers. They'll just keep changing parts until it works.

My DH said the same thing. :lol: He did, however, say that the guy was at least guessing at the correct parts for the problem she is having. That's better than many!

You're likely not going to get anyone better than a repair guy to come out, though, unless you know an engineer or a particularly amazing service business.

Halt At X
Aug. 10, 2010, 12:44 PM
You're likely not going to get anyone better than a repair guy to come out, though, unless you know an engineer or a particularly amazing service business.

Yup, it's true. My husband has never done residential a/c. He says that's for the guys who can't hack it with the big boys. He's only been in the field for 18 years and is the youngest guy at his company, but he's also the lead technician/field service supervisor at one of the largest ac contractors in Mass, so I love ac. It keeps us cool and pays the bills :)

Aug. 10, 2010, 08:13 PM

I guess the unit is working correctly as it is amazingly cool in here. Early this morning (4:00am) the unit never clicked on until 9:30am and the temp inside held at 75 degrees and was very comfy. It was cool outside and there actually was a breeze so I rode at around 6:30am.

When I came back inside the house was quite cool. I think I am a happy camper.