90340 HVAC Relay - NEED TO KNOW INFO

[@alfonsobenitez8574]

Very professional explanation, I am retired licensed state HVAC, I don't do much work anymore, but I keep watching videos to keep my memory sharp, I am 68 still active. Thank you for taking the time to share your knowledge.

[@johnjennings-JJ]

It isn't much knowledge! I do try to keep thinking about hvac stuff because we do lose some of it when we stop using it. Stay sharp and thanks for watching.

[@coolramone]

Hey can one of you guys more experienced than me tell me, what if you run the yellow wire (cool) from the thermostat to the condenser AND to the blower motor in the air handler? Can you wire it that way?

[@johnjennings-JJ]

Depending on exactly where you do the connections the answer is "Sure"...when the t'stat calls for the contactor on Y it will also call for the blower. But, when the t'stat calls for the blower on G it will also call for contactor too! So make sure if you do something like that you think about the flip side of the coin. The old school mercury t'stat had the G and Y physically tied together like you are thinking. W just turned heat on and the unit would turn the blower on. Nowadays the digital t'stats do the same thing through the programming and initial setup. Hope my 2 cents worth helps.

[@coolramone]

@@johnjennings-JJ In that case could you connect the yellow (cool) and green (fan) to the same terminal on the blower motor contactor? Or would you need a second contactor?

[@johnjennings-JJ]

You could put both Y and G on the coil of the blower relay/contactor if you had room to do it but that ties in to what I was saying before, if you just wanted to circulate air and run G then it would also run the compressor each time. Depending on what you are trying to do with the circuit/operation...just remember that the more stuff you tie together the more precise you have to be with the wiring. Are you trying to do something specific or just tinkering around?

[@CHOMAHOMA]

Great. Thank you. I am Learning A LOT.

[@johnjennings-JJ]

Awesome..

[@joe-hn9fd]

Great videos, very helpful.

[@johnjennings-JJ]

Thanks

[@andybauer4363]

Great videos. Thanks John

[@johnjennings-JJ]

Thanks.

[@coolramone]

“Typically” what are the two power sources coming in on 3 and the other on 2? 14:00

[@johnjennings-JJ]

The way that a lot of manufacturers use the PSC blower by having 1 speed for both heat and cool mode operation leads me to say that you have a direct wire from L1 coming into terminal 3 and also a wire from the load side of the heat relay switch bringing L1 into terminal 2.

[@griffinbrown1182]

Hi there! Currently replacing one of these on my woodburner furnace. Should this get hot amd hum when power is applied??

[@johnjennings-JJ]

I have seen a lot of them get warm to the touch and hum too. Seems normal from my experience. It does have electricity flowing through it. I guess you could go with a circuit board setup but that might take some modification...may be a little quieter.

[@bluegrassdna5572]

There's no difference between them. I think I will use that next time I explain it to a new guy in the field. Too many guys sourcing power to ground and getting confused or don't know how to check a fuse with power applied. Thanks.

[@johnjennings-JJ]

Never like checking to ground. I try to tell my guys that you always check back to your power source. Thanks for watching.

[@realSamAndrew]

How do you check a fuse with power applied?

[@bluegrassdna5572]

Across both fuse points. If you read voltage between both ends of your fuse, the fuse is open.

[@johnjennings-JJ]

(Something happened and I couldn't see the comment but i agree with BLUEgrassBLOOD on this one)

[@realSamAndrew]

@@bluegrassdna5572 but what if you're not sure if power is flowing? Open fuse (or closed for that matter) reads zero voltage there also. It's really tricky to me.

[@masongriffith8559]

At the 16 min mark you should put the black probe on a ground and then check, that would be the best way to explain it. You would have 120v at the wire you are checking if the light is on. The power difference you are talking about is correct but makes that explanation hard for some people.

[@johnjennings-JJ]

Thanks for the insight and comment. Since doing this video I have tried to put a few checks in "to ground". I even did a video on why I don't like to use ground for a lot of voltage checks but that is beside your point. I think for this video I wanted to do some checks to ground but to honest...that board wasn't grounded! I'll try to include more in the future. Thanks again.

[@EyeForKnowledge.]

A switch is a switch. A relay works the same as a contactor or a sequencer. 24V coil, power in common out. I had a hard time with relays and sequencers until I came to the realization that they work the same as a contactor.

[@johnjennings-JJ]

Sounds simple now but I remember calling my supervisor 5 times a day...once upon a time. I try to tell these new guys I see that "you hear me but you ain't listening" !! If they could truly understand and get it in their head that a switch is a switch...just like you said boss. Thanks for commenting and checking it out.

[@franknovak7933]

Wow ! Of all the videos Ive seen on relays this is one of the best ! Thxs for sharing your well explanation on this subject you are truly a professional .I subscribe to your channel after seeing it ! Thanks again

[@johnjennings-JJ]

I appreciate it. I just hope it helps. There are a lot of ways to get mixed up on switches. I have been there and done it myself too many times.

[@Sbrabson04]

Thank you so much for your knowledge. I kept getting hung up on why I didn’t have voltage

[@Okie-Tom]

Your demonstration board helps. Understanding voltage drop and voltage potential screws a lot of people up! Thanks

[@joselora6169]

nice and I'm assuming all thr common wires are in a 1900 box or on a board if there is one

Maannn!!! ... I just came across this video,,, Thanks for putting this info out. It has help to clear up a lot of my cob webs.

[@philochristos]

Why would there be 24 volts across the two terminals when the coil is one continuous wire from one terminal to the other? Shouldn't there be zero volts?

[@johnjennings-JJ]

It is a "load" in the 24v circuit. It is the one thing we are powering and consumes the power. If checking voltage at a load you should get XX amount if working and a switch in the same circuit would be 0 volts as that load works.

[@That_40yrOld_Dad]

Is that relay anything similar to the 12-wire plug-in on the circuit board, I see it's numbered just like it

[@johnjennings-JJ]

The circuit board plugs can be/are a little different than this relay. The plug can have both high and low voltage going through it in order to check safeties and flame sensors if it is in a furnace. The relays on a circuit board are typically those raised black boxes on a circuit board.

[@smacleod69]

Could also describe the change in path or direction of voltage like a railroad track switch. NO position you want it to left. NC having the voltage go right.

[@johnjennings-JJ]

Never thought of it that way, i like it.

[@paulbryant68]

light bulb just came on in my head too! thx great example

[@RC-Heli835]

I have one 90-340 to turn the inducer motor on in my old Rheem gas furnace and a 90-370 which G controls for fan. Whether I'm in heat or cooling mode, G flips the 90-370 relay to turn the high AC fan on immediately on startup. When the thermostat is satisfied and G goes away, then the medium fan comes on at the normally closed contacts of the 90-370 which runs also through the fan limit switch and will run the fan until the furnace cools down to 120 degrees and the fan limit shuts the blower off if the furnace is on. That circuit stays hot until the 90-370 is pulled in. This is how I found it! Can you recommend a better way to set this up? I want the heater fan to come on with the fan limit switch when temp gets to 80 degrees, run on medium and stay active to cool the furnace down after W and G go away. What I don't need is the Fan On switch at the thermostat to turn hi fan on while the heater's medium fan is on. I basically don't need G to function if W is calling for heat. Thanks for sharing!

[@johnjennings-JJ]

I think the equipment should control the fan in heating mode anyway...like you were saying. No 'G' when 'W' is calling. The thermostat should be setup for that whether it is an older one or a new digital one. Not knowing if you have a digital tstat or not, I would say check the programming. There is an option , or a selector switch, that will, or should at least, prevent the 'G' from being energized on a call for heat....that is, unless you have a thermostat problem and 'G' is energized due to that (but I doubt it)

[@RC-Heli835]

@@johnjennings-JJ Thanks I found a way to control G while W is on. The trick is to let the W relay send power to the G relay for medium heat fan while W is on or off. Then if G comes on without W it turns power off to the medium fan and turns on the high AC fan.

[@juangallegos5752]

Eso está bueno

[@johnjennings-JJ]

Thank you.

[@JS-ur8lw]

I really enjoy your knowledge and detail on explaining Components. I've been doing HVAC for many years now!! Your videos are what I will show my young techs coming in!!! Thank you for taking the time and doing this!!!

[@johnjennings-JJ]

Appreciate the kind words!

[@gotchaplumber]

Great explanation!

[@ignacioalmaguer3132]

how do you determine how many n/o or n/c do mi have

[@johnjennings-JJ]

If you are looking at a relay it should have a sticker that shows you or tells you. It may even be "drawn in" to the relay itself. You would notice it is a raised part of the surface of the relay. If you can't see any information on it I would not use it. Just get another with the specs that you need.

[@Seeykulatahy]

Thank you very much

[@johnnyriser8519]

Thank you so much for the straight-forward, simplified explanation. You are an excellent teacher. Thanks for sharing!!

[@ponzo1967]

By far the clearest explanation of a basic relay 🤔😁💡

[@johnjennings-JJ]

Thanks

[@theonetoday]

Hi My 90-340 is 8 pin for 8 pin socket. Will this 10 pin 90-340 fit my socket - extra coil blades hang over the socket and not touch anything?? I cannot find a different marking or part number for 8 to 10 pin 90-340????

[@johnjennings-JJ]

Never seen a 90-340 with a socket before. I have seen more 10 pin than 8 pin but never a socket. I would think in a pinch you could clip off the extra 2 coil connections and make it work though...but that is just me.

[@theonetoday]

@@johnjennings-JJ Thanks John, I have a White Rodgers 90-130 Fan Control Center that has the socket - 8 pin. My relays are not marked but the spec sheet shows the 90-340. All pics of the 90-130 have an 8 pin socket?????

[@teklesenbetgebreamlak7365]

Thanks for the great details explanation how it works fan relay really l wasn't understanding clearly lam new hvac apprentice thanks again

[@johnjennings-JJ]

No problem. We all were new hvac guys at one time. Thanks for watching.

[@GotchaplumberGotchahvac]

Will you do video explaining difference between 90340 & 90380 relay? Thank you.

[@johnjennings-JJ]

I will try to get to that one. Thanks.

[@jacobreinen5392]

Phenomenal job articulating technical content in a clear, methodical, and meticulous manner. It is so very much appreciated! Please keep them coming!

[@johnjennings-JJ]

Thanks.

[@christianurbano1483]

One of the best explanation I’ve seen so far.After watching it I said I must suscribe to the channel,Thanks .

[@johnjennings-JJ]

Thanks. Relays and voltage checks got me early on so I put this video out just to try and help someone else.

[@jetko43]

THANK YOU FINALLY UNDERSTAND SWITCHES. I WAS THAT TECH

[@johnjennings-JJ]

I think we all were...thanks for watching.

[@hugogarcia7574]

Thanks has you said I finally understood this relay thanks to you

[@johnjennings-JJ]

Thank you.

[@hvactipsnow9892]

Good information and video quality....Easy to follow instructions on all aspects of the power duty relay!!! 😎

[@johnjennings-JJ]

Thanks! 👍

[@ritchpoint]

Thanks for a thorough explanation

[@johnjennings-JJ]

No problem. I hope it helped a little bit if you needed it.

[@argenismoreno7253]

Thank you so much, from Venezuela

[@johnjennings-JJ]

Thanks. I often wonder how different the ac unit is other countries...

[@realSamAndrew]

Why is it called 90-340? Do those numbers mean anything or is that just the part number and people learned to call it that? For example, a 35/5 capacitor means the mfd level on 2 different circuits. 90 and 340 mean anything??

[@johnjennings-JJ]

More or less just a part number from the manufacturer. There is a 90341 and 90342 as well. The 90340 is a double pole single throw relay with a 24v coil. I think the 90341 is just one with a 120v coil and 90342 is a 208v coil.

[@realSamAndrew]

@@johnjennings-JJ thanks for the quick response. Just a note to clarify-- isn't the 90340 actually dpdt ? That's what other sources list it.

[@johnjennings-JJ]

Sorry. Yes it is. I meant to put down that down but I guess I got caught up typing. My bad.

[@johnjennings-JJ]

I think it was all that turkey and ham talking from this past week!

[@balfretsoriano4795]

Thanks again and it was a great teaching!

[@johnjennings-JJ]

Thanks

[@marshallstephens7356]

Fantastic video. Thanks so much for sharing!!!

[@johnjennings-JJ]

Thanks .

[@darrellwofford405]

what would cause to burn off the element from the relay

[@johnjennings-JJ]

Loose connection maybe...that would generate a lot of heat at that particular point in the circuit/wiring.

[@darrellwofford405]

@@johnjennings-JJ I not a electrician so it done it 3 or 4 times I was thinking it was a relay or something thanks for replying

[@1971omi]

Great explanation. Great teacher

[@johnjennings-JJ]

Thank you.

[@tercyalexanderdiaz5157]

Finally understood.

[@johnjennings-JJ]

Can you teach me...i am still trying!

[@olurotimiadepitan5087]

Thanks for your wonderfully helpful videos. So high voltage goes from the transformer to the relay normally open. Is this necessary for the relay to power the fan?

[@johnjennings-JJ]

High voltage relay comes from the main terminal block but some of the units will have it coming from the transformer only because it is a closer connection to L1 or L2. Either way of supplying main, high voltage power is needed in order to power the fan motor through the relay in a cool mode operation or just fan "on" operation.

[@justiniancasillas1069]

Thank you this video has taught me more about relays than my hvac school has taught me

[@johnjennings-JJ]

Got to start somewhere...lot more to learn!

[@devinwilliams3489]

I have an old furnace with single stage a/c that has had it's original nordyne control board that connected to the thermostat and controlled everything replaced with a packet pr380 relay. Do you think that was an appropriate repair? The system does work

[@johnjennings-JJ]

I am not exactly familiar with all the nordyne controls and there are a lot of reeplacement components out there for professionals to use. Personally, i can and have used a "universal" part to fix a customers system and it worked fine. I would say if it works properly...i wouldn't worry about it.

[@mts7274]

9:10 ...my old Honeywell relay had only 8 terminals, but the replacement part has 10 like the one shown here. The circuit schematic [numbering] molded into the plastic back is exactly the same, though. Do I need to use those terminals on the very edge (where your thumb is)? I can't imagine they can be left open or uncovered, but there aren't any extra wires to attach there.

[@johnjennings-JJ]

No, not necessarily. They put two male terminals on each side of the relay. As long as you put your 24v common on one side and the 24 "hot" (like the green wire) on the other side of the relay it should be good. They give you 2 male terminals on each side as an extra to maybe connect another 24v wire to it from another relay. Only use what you need!

[@mts7274]

@@johnjennings-JJ Thanks! Yeah, the replacement part from Grainger looks EXACTLY like the original OEM part except there are four terminals on either side instead of the original three on each side. And the replacement is like $80 cheaper than an unused [discontinued] OEM relay. Same voltage, amps and everything. Peace!

[@theprofessor5584]

Very good video, really like the way you explain things

[@johnjennings-JJ]

Thanks.

[@migneg485]

wow thank you!

[@johnjennings-JJ]

Your welcome. Hope it helped.

[@kyle_187]

What happens if you voltage to ground when the switch is closed will it say 120 or still 0?

[@johnjennings-JJ]

If you check voltage to ground at the switch when it is closed you should find 120 on either side of the switch. Watch out checking voltage to ground though, it messes with a lot of people.

[@viper22304]

Thanks for sharing the video. Could you share how you have the set-up so i could practice and understool how it works.

[@johnjennings-JJ]

Sure thing. I have a video that I haven't posted and was waiting to make it public but it might be something you could use. Try it and see if it works. kzbin.info/www/bejne/imq2goCFn6qbjdE

[@GB-ue6wr]

Great explanation!!

[@franklinknight1460]

wonderful grate teacher very good explenations

[@johnjennings-JJ]

Thank you.

[@treyfurniss6576]

Very very helpful thank you

[@johnjennings-JJ]

Thanks. Switches can be confusing sometimes so I hope this does help a little.

[@LaughLiveLove563]

Great video , thank you !

[@johnjennings-JJ]

Thank you for checking it out.

[@bakemmmmm]

You doing so good

[@johnjennings-JJ]

Thanks.

[@simmonsjr25]

Awesome video and info.

[@johnjennings-JJ]

Hope it was helpful.

[@markferguson3477]

Great video but I would like to see how u wire the circuits

[@johnjennings-JJ]

Thank you. That video is actually on my list to do in the next month.

[@markferguson3477]

@@johnjennings-JJ cool, looking forward to see that video. I'm very young in this trade and the stuff u talk about school doesn't teach me those.

[@johnjennings-JJ]

I don't know if you really wanted to see the wiring of circuits on a practice board or a real unit. I made this recently in preparation for some stuff I have going on next month. If it is what you wanted to see, let me know what you think as I have it unlisted right now. If you don't watch it it is no big deal. Thanks kzbin.info/www/bejne/imq2goCFn6qbjdE

[@markferguson3477]

@@johnjennings-JJ k, will do

[@dammo361]

Best video in explaining the voltage part on relay in the most simplest terms... 💪🏼🧰🥷

[@johnjennings-JJ]

Thanks

[@helpme1202]

Where can I get a training board like this from?

[@johnjennings-JJ]

If you want to spend a lot they sell training boards like this one for a grip. We took a piece of 1/2 plywood, some paint, and the components we wanted to teach on to put together our own. Much cheaper and still just as good. Just figure out what you want on it.

[@damon8201]

Very detailed video. I'm gonna share this with my fellow techs and all the rookies. 🫡