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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8326
Experience:  Furnace, A/C and heat pump specialist.
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I have a tappan ehc52-36-41 electric furnace. Hooking up a/c.

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I have a tappan ehc52-36-41 electric furnace. Hooking up a/c. The diagram does not show what to hook up to terminal 4 on the blower relay. Any help?
Hello. My name is XXXXX XXXXX I'll do my best to help. Troubleshooting often requires meters and test equipment. Let's get started and see what we can do.
This number is XXXXX showing up as a good model for a Tappan furnace. Any other model number on the furnace label?
Customer: replied 4 years ago.

Tim, finally getting back to you. No, no other model numbers. I am not at the house now but I did take a photo of the 24v terminal strip and the wiring diagram. There are instruction to remove the jumper from the blower relay terminal 4 and 6. It refers to using terminal 4 for cooling and 6 for heating. It does not have a "y" on the 24v terminal strip.

Can you upload that here?
You can upload the pictures using the tiny pic site .
Here is a link to the site.

Click on Browse , select the file from your folder.then click UPLOAD NOW.

They will give you a quote to enter in the box to verify you are a human.Enter the quote and click UPLOAD NOW

You will see your picture on right side of screen.

Then copy the link URL for email & IM

Paste that link here on the site.
Customer: replied 4 years ago.

View Full Size Image


I hope this is what you need. Is what I really need is hooking up the 24v from the condenser and thermostat.

I can not read them.When I enlarge they become blurry.graphic
Normally though your thermostat wires will connect r and Rc from thermostat to an R on the terminal block for 24v power. Green to G for fan. white to W for heat, blue or whatever from c on thermostat to C for 24v common. The Y from thermostat does not connect to anything on board, it just goes straight to outdoor unit.Then a wire from C also goes to outdoor unit.
Customer: replied 4 years ago.

Good Morning Tim,


First this furnace is so old that it does not have a circuit board.


The terminal strip is labeled as follows:

R = red wire from thermostat

G = blue wire from thermostat

O = no wires


W = both W1/W2 & W are jumpered, black wire (not sure where it is comming from as I am not at the furnace) connected to W1/W2 along with white wire from thermostat and yellow wire connected to W (again not at the furnace) but they go to the blower relay.

E = no wire in or out

C = no wire in but out to terminal 1 on BR

OTC = black wire in (not sure from where) no wire out

OT-1 = yellow wire in (not sure from where) no wire out

OT-2 = no wire in or out

OT- 3 = no wire in or out


The otc connection show that if anything is connected it goes to the EHR


The thermostat wires only have 3 wires but there are 2 of them. One is not connected to anything(the other is connected as mentioned above) so I was going to take the red wire and connect it to the y connection at the thermostat but did not know where to connect it at the furnace. Now is I understand you correctly, I can connect that right to the 24v wire coming from the condenser and connect the other to the c terminal.


There is a note on the diagram reads as follows: Remove black jumper wire from blower relay terminals 4 & 6 for 2 speed operation. (Terminal 4 for cooling and terminal 6 for heating).

That is the only reference to cooling on this diagram.


I hope that I am on the same page as you as this person is a good friend but really is to cheap to update his furnace and has asked me to hook up the a/c. I don't want to hook it up and blow something out and now I am stuck for a new unit.


Can you please add my work email [email protected] so I receive it at both accounts?


Thanks Roger

After I saw pics, i realized there was not a board as we have in today's furnace, I was referring to the little terminal board (strip). The 4 and 6 on the relay just control what speed blower runs on in heat and cool modes.Sounds like they have a jumper between 4 and 6 so we are using same speed on heat and cool. Going to outdoor unit , all you need is a Common from the indoor transformer and the hot coming straight from Y at thermostat. The Y is really the opposite wire from transformer which goes to R at thermostat. Thermostat is just like a light switch.When you have thermostat off, the circuit is broken to outdoor unit, but when you turn to cool. the circuit closes and goes to the outdoor unit.

By the way JA will not let us communicate outside of the site.Emails and phone numbers are blocked.

Customer: replied 4 years ago.

Tim, so if I am following you right, the wire from the r terminal/thermostat goes to the #4 lead on the transformer. I would connect the y to the #1 lead of the transformer which goes to the fuse link of heater element #1.(I don't think this is right because of the higher voltage. In this case with no circuit board which for the y connection on the board acts like spicing 2 wires together, I would think I could run the y wire right to the condenser. Correct me if I am wrong). Then just connect the other wire to the c on the terminal strip. I am just trying to be extra cautious on this job seeing my diagram really does not show anything.


Wire from R at thermostat connects to the low voltage transformer wire(hot) This is bringing 24v to thermostat, then Y from thermostat goes straight to one side of contactors in outdoor unit. That way when thermostat calls for COOL, the R circuit from transformer is closed to complete circuit to outdoor unit.You have a second wire to outdoor unit which connects to C (or the other low voltage transformer wire. You should be able to see what I am talking about in that picture I sent. Let me know if this helps
Customer: replied 4 years ago.

Tim, thanks. That is really what I was trying to say in my previous post in prentices, but you are better with words than I am. That should be all, I was on the right track all along, just needed to get it confirmed. rather be safe than sorry.



Thanks Roger for allowing me to work with you. If satisfied, please rate accordingly.Feel free to come back for follow up.
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Customer: replied 4 years ago.

Tim, just a follow up, all went well. Everything works great. The a/c side of it was good, but the blower would not run. This furnace has 2 60amp breakers and three fuse links. Two of the fuses were blown. Like I said a old unit. I think it was made to heat Noah's Ark.

Thanks again

Thanks Roger for allowing me to work with you