How to Diagnose a Bad Furnace Pressure Switch (5 Easy Things to Check in 2021)

[@bratmd]

After following advice from so many videos, I cleaned out the pressure tube and port. This was the only video I found that suggested this, (and service wouldn’t be available for another 1-2 days). I have heat again. I am so grateful for your video.

[@keithmckay8746]

I've been in the hvac field for 5 years now out of trade school. And I've had my fair share of failed pressure switches. But I love your video and how detailed and organized your tips and instruction was! Great job! This will be very valuable to everybody just starting in the field!

[@timrowe8953]

9 times out of 10 it's not a bad psi switch

[@sillyworm]

My 90 year old Mother..hearing an odd noise from the furnace lowers the thermostat because we were leaving the house on Thanksgiving.We find out..she called the company that put the new furnace in to see if there was a problem.It's the Friday after Thanksgiving...somehow this is a Holiday(?)..they charge her $180 to come out and replace her pressure switch..total $489.00...it's a 5 year old furnace.See what's happening here? Companies sell junk....and make a living repairing junk...until it's time to purchase a new piece og junk again...and the dance starts over.Furnaces used to last 30 years.How convenient that things are now made to purposely fail.

[@keithmckay8746]

@@sillyworm to be honest I completely agree with you I now run my own company and I like to install goodman equipment because it straight forward and easy to get ahold of for customers. I find that the quality of everything no of days is crap they build them to break on purpose. Just like car and everything els no of days its all just plastic and aluminum junk. But that's the world we live in sadly

[@keithmckay8746]

@@timrowe8953 yeah usually its something that plugged up the vacuum/ pressure hoses. Especially on 80 82% furnaces but on 90 or condensing furnaces pressure switches usually fail due to water getting inside and gunning the up because the inducer drain is not draining. You must be a super tech with that energy you're giving off lol.

[@toronto690]

​@keithmckay8746 how much is a pressure switch and where to buy online? How much is fair for an hvac company to replace it?

[@allanw.gackstetter7969]

Great video….36 years working with controls…… your videos are beautifully articulated. Thank you 🫡

[@ReggieRooner]

It's 2023, January, and we lost power for multiple days in a snowstorm. Power comes back but the furnace doesn't work. I found this video, and it worked to fix the pressure switch so that heat is flowing until I can get a tech out. Thank you for the video!

[@manfredman5075]

Man, thank you brother for listing the turning on operation process. I found water in my pressure switch was causing the the igniter and valve steps to not initiate. Dumped out water then let it dry and after reconnecting it voila!

[@ChanceBerryman]

Thank you so much for this information. My furnace was short cycling because the pressure switch port was clogged, just like you showed. Peace and blessings to you and your family. I can't thank you enough. It's snowing and cold outside and my house was freezing.

[@foxfamilyhvac]

Great. Glad you're up and running

[@joellasseigne4652]

Wow! You just saved me a ton of $$$. Collection port was caked with substance. Had to use a small drill to clean it out. Thank you!

[@foxfamilyhvac]

Awesome Joel!

[@parry1]

What a fantastic video! Walking through overall process of operations and specifics.

[@7julio421]

I just want to thank you for the time to share the information i was able to fix my problem with your video God bless you and your family 🙏🙏

[@adammercado1344]

Im a 3 year HVAC Installer who’s trying to gain more knowledge on Servicing & to be completely honest, I love watching Fox Family’s Videos because He’s so professional, organized, and they know all aspects of the furnace. Amazing; Great videos !

[@marcgarza859]

Thank you for the advice of checking all the lines for water. Just saved me all the time of going out and finding new pressure switches.

[@juanguzman2056]

Good job👍Nunca había visto y escuchado toda esa explicación. Eres un gran maestro. God bless you for ever. No hablo mucho inglés, pero entendí casi todo.

[@colonelbuckshot2914]

Thanks bro, I just fixed my furnace with your help, I appreciate you.

[@foxfamilyhvac]

Awesome!

[@virgil3241]

Another great video for us homeowners who arent experts, but at least can try a few minor things before calling a tech. I always feel accomplished when I fix minor things like this

[@danlusby1246]

Awesome video! Thank you so much for your helpful advice! I was able to get my heat working again, just by cleaning the blower port, where the tube connects, just like you suggested. I will definitely be calling you when I have more serious problems. Thanks again!

[@jasonfreeman3722]

Recently had a service call to a residence for a furnace. The home owner was a retired electromechanical engineer. She had called her usual service company and they changed psi switch with aftermarket w/o even mounting it. Plus switch rated .65, however, equipment called for .3. That didn't fix it so they condemned the board. While installing the new board it became damaged. Sustained a crack at the electrical connection. Whenever she called them 3rd or 4th time service company stated that they were not going to continue to work on old equipment. I found debris inside inducer housing. Unit was startup and run then shut down. That's when I discovered psi switch rated too high for system. Sourced correct one and unit ran correctly. Next day had a call back, that's when I discovered the cracked board. When it's time to replace her equipment I believe she will use us.

[@carlcohen3164]

Tap the switch did work for me.will get a new one. Thank you.

[@robertsneed3]

Thank you sir for sharing this information about the pressure switch. You were very detailed in the different causes that can make your pressure switch inoperational. #PEACE✌🏾

[@tmack7563]

best video on this subject thus far, thanks a million. peace!!!!

[@melvinmccoy9830]

Great description. I'm sure you are a good instructor. Thanks for the lesson.

[@caru3257]

I got the best lesson on how to troubleshoot a pressure switch yesterday.

[@waterjoe2024]

You can used a wire to bypass the sensor to proof it is not working

[@april464]

Thank you for sharing this video! My furnace quit due to the hose from the pressure switch to the chamber. It was more horizontal than vertical ...Cheers from Ontario, Canada!

[@KellyGummelt]

There were bugs in my pressure switch tube. Thanks for the help!

[@j.e.b.206]

Great video! Thanks for sharing.

[@sjf271]

Had to subscribe if only because we have the same last name! I do appreciate the great content and easy to understand explanation.

[@MinhTran-nz6hv]

Your trouble shoot clip is awesome. It helps me to trouble shoot successful my pressure switch and replace it today 👍

[@timklein3962]

Excellent video; easy to understand and covers everything in proper order; thank you !!!

[@iadc43]

Excellent description of how this works. One thing that could be mentioned is that “fooling” the system by shorting the pressure switch wires (closed switch) after the inducer starts may let the burner fire up, but will lock down the system the next time it tries to start, should somebody notice it would run if done that way once. In that situation, the inducer won’t even start to run.

[@gregmercil3968]

There have been times where I’ve bypassed the pressure switch for testing purposes, and more often than not the system won’t even start up, or throw a trouble code for “pressure switch stuck closed.” I figured out a way around this, by jumping the two pressure switch wires together right as the inducer is ramping up, tricking the board into thinking that the pressure switch has closed properly. (Once again, I do this for testing purposes ONLY.)

[@Talentman18]

Great video thank you!

[@mdotto8707]

So to make sure I understand, if the Ignitor is coming on that means the pressure switch is working properly? My inducer motor comes on, the ignitor lights up but the gas valve takes a while to click on. I have noticed that the gas valve will click on as soon as I take the side panel off. It's like an air flow issue. As soon as it does, the burners all light and the furnace heats normally until the thermostat shuts it off. Thank you for your videos! We appreciate you sharing your knowledge!

[@myrentalhouse]

Thank you so much and this video has saved me lot of $

[@glenbailess4049]

Great information and useful, thanks for sharing...

[@bceh113]

Super helpful. Concise and extremely easy to follow.

[@TheMatski1955]

Thanks for the video I’m having this problem and your explanation helped me solve this problem

[@foxfamilyhvac]

Cool! Glad to help!

[@sridharnarayanan999]

Thanks. Not sure what fixed my problem (pressure switch stick open) - puffed switch & clicked softly , tapped it, was not fully vertical so refixed, cleaned metal "nipple" om motor where hose fitted with electric wire like u suggested, no water in hose, reset power switch couple times (separately cleaned flame sensor, unconnected) and BAM - my Goodman 80% single stage started again. APPRECIATE THE HELP - CHEERS!

[@foxfamilyhvac]

That's awesome!

[@KetoJames]

What if the induced motor isn't kicking on, but the code given is a pressure switch.

[@patrickegan5308]

Very well put together and informative.

[@nathanworley3148]

You guys saved my butt thanks for the video I was able to troubleshoot and fix my furnace myself thanks to you guys

[@foxfamilyhvac]

Awesome!

[@JVA55DJ]

Nice video Sr...thanks

[@beckylawler2768]

I hope you're reading and responding. As long as I was blowing into the hose that leads to the switch the green light was solid, but as soon as I quit blowing the green light started flashing again. There is a second hose between the switch and the the flue pipe but it's more difficult to remove from the switch so I didn't force it. Suggestions?

[@tomw3689]

At 11:27 do you say that backwards? Should you get 0v if it's open and 24v if it's closed?

[@jimbarron8688]

Here are the values for a 24v switch: with one lead on ground you should see 24v on the power in wire all the time. If the switch contacts are open you should not see 24v on the power out wire. If the switch contacts are closed the power out wire should also be 24v. Next: with both leads on the switch you should see 24v across the switch when the switch contacts are open. When the switch contacts are closed you should see 0v across the switch. It is all to do with potential difference. A multimeter set to voltage is really a potential difference meter that see the difference between the two points of contact. A closed switch has 24v on both terminals therefore 0v potential difference across the switch.

[@ivancioclea2971]

Thanks for this video brother

[@Rob-pg7rb]

I replaced my inducer motor and blower wheel because of bearing noise. Got them separately on Amazon. Now I got a lot of orange flame. Flame looks like crap. It was nice and blue before. Also seems like the flames are not being pulled/stretch enough inside the exchanger because the flames are not a narrow as before. Maybe didn't adjust the fan blade on the motor shaft far enough out? Maybe the new cheap Amazon blower wheel sucks? I got a nanometer, but haven't checked the vacuum on the inducer yet. Not sure if the manual has a spec or not.

[@ttight11]

This is a great video! Very organized and comprehensive. Thank you! Unfortunately, my problem persists. I've had multiple HVAC techs from multiple companies try to fix my furnace, but all have failed. I cannot be too hard on them though, since the issue is intermittent, and some have not been able to recreate the issue. I have a 7 year old Ducane, 95% efficient gas furnace. The issue: Randomly fails to fire (inducer running) or fires and blower runs, but shuts off before set temp is satisfied. Compounding the problem is the fact that the system does not re-try. If I lower the set point on the T-stat, and then raise it again, it usually works fine. If it happens a 2nd time, it'll fire or fire and stay on on the 3rd or 4th try. The obvious intolerable problem is when we are asleep or out of the house, so unable to manually cycle the call for heat. This has been the behavior since the first winter. Installer threw his hands up. Lennox expert has replaced parts but never fixed. Next step is a whole new system. Any thoughts or suggestions will be greatly appreciated!

[@drinflfl430]

Video created a few years ago but asking how to determine the vertical position on a pressure switch (i.e. a clock rotation or a flip of the switch to lay flat or upright). Have found NO answers anywhere??? Thanks

[@jmurphy6740]

Appreciate all you do and your videos wish you would just give one video when enducer motor has been replaced and still no power. START THERE.. what powers this motor.. CONTROL BOARD ALSO WAS REPLACE???? WHAT NOW???

[@lawman4life1]

I have a two stage Carrier Inifinity HVAC furnace and I started getting a LPS trouble code. Upon observing the furnace it will go through the proper cycles and once the blower starts blowing low air the furnace will trip the LPS code and then shut off only to restart again in high fan mode and resume heating just fine. This seems to occur almost every time now. I had an HVAC technician come out today and he said that it could be the pressure switch or it could be a defective control board or a defective thermostat. I started by ordering a new pressure switch as that is the cheapest of the three parts to see if that will solve the problem. I'm curious to know what your thoughts are about this issue and if you think a new pressure switch will solve it or am I looking at a much larger problem. Of course his recommendation was a brand new HVAC system Thanks in advance!!

[@richardwuttunee125]

Hey Greg , u guys ever use the sdmn6 I believe it’s called , the manometer with a pump on it to conclude if the pressure switch is indeed closing when it’s supposed to?

[@hotfeva9843]

What if pressure switch is stuck closed?

[@DavosJams]

Great stuff, explained clearly 👍

[@raybunting7398]

Great video.

[@johndumoulin5808]

fantastic video! thanks

[@swang4263]

Thank you for the video! My issue is a little different. My furnace worked well for about 25 years, but recently the pressure switch frequently failed (every few days or weeks). Every time I can fix it by sucking out an ounce or so of rusty water from pressure switch hose, and clean and dry the hose. How can I prevent it from happening so frequently? Thank you in advance for help.

[@chickenandonions]

awesome vids man !!!!!

[@justwork_hvac]

Thank you for sharing your great video's..keep them coming

[@JT_70]

The induction motor on my heater is not coming on. It is receiving 120v. Could this be a pressure switch problem or is it more likely that the induction motor has failed? The unit is about 16 years old.

[@reeseerchguy3771]

By my understanding of the video, the initial running of the induction motor doesn't depend on the pressure switch being closed. It's the other way around; the switch can't close until the induction motor runs for a few seconds to generate the partial vacuum. I would say you have a failed induction motor. Hope this helps a year later. :-)

[@l.a.m7645]

I had a code on a Rheem gas furnace pressure switch open. System would start in sequence and run about minute and a half and completely shut down and will not try to re light code blinks 2x with 4 sec pause saying pressure switch open. I checked hose cleared port checked flue I'm assuming the pressure switch is bad?

[@chancecooper4006]

Love the videos!

[@Shylock15]

What does it mean if the inducer motor attempts to start but then shuts down almost immediately, like after a second or so? Mine does this randomly and then starts running after a five minute delay.

[@johnaries9301]

Can you wire a pressure switch backwards?

[@toronto690]

How much and where to buy a pressure switch?

[@ThomasHegland]

If you don't have a Manometer, what is a practical feel for the vacuum? My pressure switch is not closing. I think the switch is OK. It passes the suction test by gently sucking on the tube. I just replaced a broken Inducer Fan\Motor. The amount of vacuum is very low on the port. I put a piece of paper in front of the port and it pulls the paper to the port, but if you use your finger, you don't really have any sense of a vacuum. My switch says 1.11 WC

[@victorbautista3639]

Hello, a question, what can I ask if the pressure switch does not receive 24 volt from the board

[@joeyberry5451]

I have this same problem now, did you ever find the answer?

[@12345lynduh]

10/06/23 I wish I could convince the installers that installed my new A/C to move the thermostat back where it was. It was in the hall. Exactly what was mentioned in this video. It is now in the living room with a supply register on the floor near the thermostat. I've blocked the air flow the best I can, but doesn't look good and thermostat isn't cycling on and off the way it should. I asked when he was moving it, if that's ok to put it there. Just venting. Thanks

[@lcasblcr]

furnace heat skipping stage 1 and goes straight to stage 2 - I've checked the flue, the hose on the switches, the filter is fine - replaced the thermostat...what do I look for now. I applied soft suction to the switch and could hear the soft clicking sound. Furnace will not heat the house even to 73 degrees when running on stage 2.

[@DavidE-es5xt]

My interterm furnace code states pressure switch is closed. Red blinks 3 times. Flame kicks on, then goes out within 10 seconds. What can I do with a closed switch?

[@faymejia7618]

Hey bro, have a problem the furnace not blowing enough hot air. I went to check and just working about 10 minutes then the limit switch open and turn off the burners the fan keeps working , after 2 o 3 minutes start working again for an other 15 minutes... keeps doing that. I don't know if the problem is the limit switch or something else may cause the overheating.

[@roberts1159]

Check your air filter first and change it if needed. Open your blower compartment and check condition of blower wheel. If its really dusty perhaps low air issue. Is the blower motor very warm to the touch or wheel hard to turn ? Check the blower motor capacitor and see if it’s within proper mfd range as stamped on the capacitor.

[@jordanbryant4022]

I agree with Robert: sounds like low airflow. Make sure all vents (especially return air) are open and unrestricted, clean filter, power off and check blower.

[@faymejia7618]

Thanks guys

[@frankjames1955]

today i checked my pressure switch, theres a little water coming out one of the teminals that wire connects to , the error code i have says limit switch ... the inducer wont run but the blower always runs even without thermostat

[@PBS-nm1uu]

which is the incoming terminal ?????

[@NormaLowe-pb7qp]

new furnace banging noise , its been 2 months now, ambient says they could not hear this . I also called the company that built this, they tell me I will have to pay another company to check this out . if it is new why would I have to pay for this?

[@cpK054L]

as i'm watching this, my pressure switch literally fell apart... that's a sure-fire way to say it's broken🤣

[@nickmoes5305]

How do I get this bird out

[@myleeelena6368]

Really nice 👌 😍💋 💝💖❤️

[@Hvacmania]

I love you ♥️

[@adamnox2268]

For those of us who only have occasional fails to start but don't want to be caught without a working furnace, and so we can't just monitor it with a voltmeter, some general symptoms or indicators of pressure switch failure would be nice.

[@logancostello8103]

Skipped the part where board verified switch is open….

[@thepitpatrol]

Never read the instructions lol.