[Smiley_80911]

Our heater has been blowing out hot air sometimes and then cold air at other times for about a month now.

Las week my mother called the people who had installed the furnace to check it out. They did some maintenaince on it and it blew out warm air for aporx. 6 cycles... Then went on to blow out cool air.

After the guy did the service on it he said that if what he did didn't fix it, that it was the Honeywell smartvalve gas control that needed to be replaced. He also that to do this it would be around $600.00.

Is this something that can be done by someone other than the HVAC guy? Or could it possibly be another problem? PLEASE HELP!! We woke up this morning and it was 62 degrees in the house :eek: with snow outside. THANK YOU

[wmproop]

How old is the unit? Is it under warranty?

[Smiley_80911]

It was purchased and installed July 2, 1999. I don't know if my mom ever registered it for the warranty or not.

[KC13]

With the probable exception of the heat exchanger, the original parts warranty has lapsed (5 years). Unless you purchased some type of extended warranty with the unit, I'm afraid you are on "out-of-pocket" terms. The "Smart Valve" control is one costly li'l bugger because it incorporates a gas control and ignition module into a single component. Wait, the news gets better: they are very prone to failure. Try this: apply pressure to the square connector at the Smart Valve while the unit is attempting to start a cycle. If the heat starts working, the SV is failing.

[Smiley_80911]

Thanks I will have to try that when I get the chance. But the thing is that sometimes it does blow out warm air... And sometimes it blows out cold air... Could this still be the SV? You said that it's a valve and an igniter in one? So it couldn't be something like the igintor switch? I don't know much about this type of stuff I just know that I can't be living in a freezing cold house.

[KC13]

If the inducer runs AND the pressure switch engages BUT nothing else happens, it is very likely a faulty SV. May not be consistent yet, but it will get there. I guarantee you will know when it does.:rolleyes:

[Smiley_80911]

How long does it normally take before it get's fully there?? I just want to make sure that this will fix it because I don't exactly trust the people who same to look at it (like mechanics) they could be just saying that it is that... Just to get more money. I was looking online to see how much the part is and if I was looking at the right thing it was around 250.00 and they told us apox. 550.00 to replace it. Does that mean they are charging 300.00 for labor?

[KC13]

I'm sure that also includes some mark-up on the part. If you have a voltmeter and the special test harness for SV's, troubleshooting is a snap. Without those items at your disposal, it becomes a bit of a crapshoot. It is fairly likely that the diagnosis was correct. If the unit is nearly 10 years old, I'm impressed that it was still working until recently. I cannot predict how soon it will fail completely, but rest assured it will. The replacement SV's seem to have addressed the problems with the originals. If you get one make sure it has a date code no older than 2007.

[hvac1000]

KC13 is absolutely correct about this (If you get one make sure it has a date code no older than 2007.) They are called dumb valves by some in the industry and had many problems. The latest series seems to have corrected this so that is why the date code is important. You do not want to get stuck with a older new one since you will probably have to replace it in the near future again if the code date is before 2007.

[Smiley_80911]

THANKS FOR EVERYONE'S HELP! The guy came today and replaced it and we have heat again. My mom was the one who was home so I don't know if it dated 2007 or whatever... But thanks for helping me make sure that this was the right problem!

[hvac1000]

Glad you got it going.