Rheem furnace blows cool air then warm

[marisakay]

New house and our first winter here...very cold winter (it is 7 now)...furnace seems it is always running....the registers first blow cool air while the furnace first kicks on..then the air turns warmer...this does not seem normal to me but I have never had a gas furnace before...this is a old large farm house but the furnace is only 4 yrs old. any info as to why it blows cool air then warm air???
also is it best to keep the fan at auto or on? it has been set at auto this whole time but I switched it just now to on to see if the house gets warmer.....there is one room that stays much cooler then the other rooms...thansk for any input..I really appreciate it!!

Marisa

[Hube]

Normally in the heating season ,the fan should be on AUTO. When the BURNER first comes on,(and the fan on control is set right) it should take approx 1-3 minutes before the fan starts to blow warm air. If the fan comes on too soon, of course it will blow cool air, because the burner has not had enough time to heat up the heat exchanger in the furnace.. If it comes on too soon, the "fan control" should be raised slightly, thus when it does come on it will blow warmer air. The fan off control can also be set to shut off when it begins to blow cool air at the end of the cycle. Hube

[marisakay]

thanks for the info, I really appreciate it....how exactly do I go about changing the fan control??? I am very unfamiliar w furnaces....thanks again

[Hube]

The type of furnace and model , fuel, will dictate the type of adjustment procedure. Do you have a manual on this FURNACE?. Some furnaces depending on the age,etc, have a control box on the front chamber wall that has adjustable (dial pointer) settings. Also, some furnaces have a Control Board with DIP adjustments which can be adjusted to give various DELAY (seconds) to fan on/off SETTINGS. These settings can be adjusted, keeping the furnaces " TEMPERATURE RISE" within the listed RANGE. (this RISE RANGE is on the furnaces spec label. If your not comfortable in adjusting these settings, its best to call in a Tech, otherwise post back with any additional info and we will try and guide you in adjusting this fanon/off setting. Hube

[marisakay]

It is is Rheem Criterion gas forced furnace and it is roughly 4 yrs old...we have no manual to it ther model number is RCBA 3765GG17..serial M0400


Thanks for any input..I would have DH do it as he is much handier then me..

Thanks

[marisakay]

any one that can give me some info onhow to adjust the fan control would be great!! This cold air blowing is starting to really stink..LOL

Marisa

[marisakay]

just bumping up to see if someone can help me ..thanks!!!

[peluso14]

I have a rheem 90 plus with the same issue, I do not have the manual but am familiar with electronic compoenents, I only see one dip switch module, and ideas?

[marisakay]

I am in the same boat, bought the house recently and there is no manual...I would lvoe to change the fan control myself if I knew where it was

[marisakay]

bumping up on this again...since cold weather is right around the corner I would love to fix this problem myself...any one w ideas on how to change the fan setting on my furnace?? thanks so much!!

[imeduc]

Have you looked at the back of the blower door. You should find the schematic there for how it is wired .It should show you how to kick up the speed on the blower. Dont forget to put new air filterin every 30 to 90 days.

ED

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