Pressure switch stuck open? 2 areas im looking @

DangerMouse · 10-30-2010, 01:53 PM

Quote:

Originally Posted by AlphaM1

cant believe this was so easy. it took me longer to find this forum, than to fix my furnace.

just wanted to say thank you. and keep on posting, you dont always just help one person with knowledge, i can tell you, this site and the members are great. THANK YOU ALL!!!!!

:thum bup:

: thumbup:

SWEET! We can only assume you had the same problem!
Glad you found the answer here.

DM

dmdonnay · 01-09-2011, 03:05 AM

I was experiencing the same problems.

The furnance would run for about 90 seconds and then would shut down and give a "pressure switch stuck open or closed" error message. I tried everything you did from dis-engaging the hose and manually testing the switch to cleaning out the end by the motor.

Nothing seemed to work

; until I took off the door to the air intake and held the safety button with my hand and started the furnace. Low and behold, the furnace ran for 5 minutes without shutting off. Then I remebered I changed the filter two days ago; right when the problem started. Since the temperature is 59 degrees in the house and my wife is even colder to me since the house is so cold

and it is 2 a.m., I am running the furnace without the filter and will be getting a new filter in the morning. The house is already starting to get warmer and I will not have to have a service call on Sunday. Thank you

**beenthere** · 01-09-2011, 04:38 AM

Air filter has nothing to do with the pressure switch. The pressure switch is for the pressure in the inducer and heat exchanger. not for the pressure external to the heat exchanger caused by the blower or air filter.

My guess would be that you either read the code wrong. or that you disturbed the right thing when you opened the panel..

likediy · 01-10-2011, 12:06 PM

Anybody know where to buy these switches with fair cost? Thanks.

My switch is definitely malfunctioning. I blew and sucked the port of the switch and used my multimeter to check the connectivity of the 2 pins. I could hear the click but the meter showed numbers between 150 Ohms to 400 Ohms, which was rediculous.

DangerMouse · 01-10-2011, 12:15 PM

I don't think anyone sells ANYthing at a 'fair cost' any more.... sorry... just ranting....
Google the model #s and switch type and you may find them online.

DM

likediy · 01-10-2011, 04:27 PM

Found this one on the web:

http://www.mobilehomerepair.com/medi...-35286-000.jpg

Mine is -1 PF. This one is -0.9 PF. It should be working, right?

Thanks.

rstevens · 10-24-2011, 01:41 PM

You might hate me for mentioning this, BUT, I went the cheap way and just replace the actual Fan Blade for $32.00 US. The only trick is you MUST know if the fan turns CW or CCW. and the measurements. I put it an aluminum fan blade and works great!

I am the biggest cheapskate ever, so DIY is my middle name! =)

likediy · 10-24-2011, 02:39 PM

Quote:

Originally Posted by rstevens

You might hate me for mentioning this, BUT, I went the cheap way and just replace the actual Fan Blade for $32.00 US. The only trick is you MUST know if the fan turns CW or CCW. and the measurements. I put it an aluminum fan blade and works great!

I am the biggest cheapskate ever, so DIY is my middle name! =)

It could be a good idea, but we have to find out how stronger suction the new blade would generate comparing to the original one... It might be hard for some DIYers...

BTW, I ordered the pressure switch shown in the link and replaced the old one. The furnace works perfectly.

william K · 10-29-2011, 05:47 PM

what motor or location of the motor

william K · 10-29-2011, 05:49 PM

The motor would humm where would that motor be located AT

Traida · 04-30-2012, 12:23 AM

Quote:

Originally Posted by grimace15

Now for that rust thing I wanted to remove. I got a small screwdirver and stuck it in the hole and all it was, was a little corrosion build up. IT WAS BLOCKING THE AIR FLOW! Now I took the other end of the tube connected to the switch and connected it to the fan and VIOLA! IT WORKS NOW.

Mind you, this is AFTER having a professional come out and tell me I needed a new control board. I had it fixed in less than two hours after he left the door. I am not paying for the visit as he could have done the same thing. Hell, I am just a pharmacist and thinking of opening up an HVAC training school!

***Same problem solved, different root cause to try***

I was experiencing the exact same problem but did not find any corrosive build up on the blower-side tube connection. I DID, however, hear some odd noise when testing the pressure switch by sucking/blowing on the tube to hear the "click" (it did click by the way indicating the possibility of working properly).

The noise resembled water being sucked. I removed the pressure switch and headed to the sink. Shook the thing and wouldn't you know it? Rust-colored water started coming out. There must have been several table-spoons of water in the switch.

I have no clue how it got in there (must have been some condensation along the life of the furnace) but after shaking it out, re-installing the pressure switch, confirming proper "switch" operation by sucking on the tube, and starting the furnace once again things seem to be working.

The water in the switch must have been causing a constant "switch open" indication.

Thank you very much for all who contribute to this forum. I hope that my issue/resolution helps at least one of you out there looking for answers!

biggles · 04-30-2012, 07:07 AM

the motor should never be hot to the touch even when running in the winter..but warm.so after the summer is over and the heating gets used more often,keep in mind that touch test.voltage applied to a jammed motor isn't the best thing for those windings and your continuity test was right on...white/black dead short,each to motor body infinity,each to the green ground infinity.chicken wire cap on the end of that PVC is a suggestion.removing the motor off the mounting plate and checking those squirrel rounds once a year is a good maint.

how · 04-30-2012, 02:39 PM

Hey Traida
This problem will probably happen again. Do you have a drain tube attached to the bottom of your ID assy that might be obstructed?

If not, having the tube from the ID assy constantly rise up to the PS, allows the forming water droplets to flow back down to the ID assy when the heating cycle ends.

laneuiowa77 · 09-23-2012, 10:32 AM

I turned the furnace on for the first time this season and nothing. I had the 3 red flashes and the manual said the pressure switch is stuck open (as noted here too). As discussed in this forum, I removed the hose and you could see debris in the outlet nipple. Removing the debris, which appeared to be rust/corrision, fixed the problem!

Thanks a ton for the helpful info on this site.

Cheloco51 · 10-04-2012, 02:06 PM

So, thanks to all of you I was able to test/clean/check things out. My error code said that the switch was stuck open and when I sucked on the tube(or let the vacuum take over) everything fired up and worked fine. But after doing everything suggested it still wouldn't run on its own.
So bad pressure switch. When I took it off I noticed a screw in the middle of it. So I popped it off to find that it was holding a spring against the switch diaphragm. So I loosened it and put it back on and got the error code that the switch was stuck closed..hmm. I then tightened/loosened it until I got no error code and everything fired up/shut off properly.

So I guess that means that my pressure switch is pretty close to kicking the bucket. Just wanted to share my experience/fix since you have saved me a service call and taught me a ton.

Mahalo!