Laars Lt400 Electrical Question

[Bugman1400]

I have a LAARS LT400 that is wired for 240V. I also have the 15-pin plug that is all RED and says 240V. I've also measured 240V across the source and coming in on the terminal strip (Red/Black). My symptom is that I get the ES1 light and the manual says to check the flue (blower motor). The blower motor does not blow, however, I am able to manually spin the motor and it seems to rotate fine. I also checked the voltage to ground and get 120V, but across the terminals I get zero (this tells me that I am only getting one phase, L1). I also disconnected the motor and checked the terminal strip and only get the 120V. In the manual it shows the 15-pin plug, but not the routing of the red wires. Does anyone have a schematic to show this or can otherwise, help me out? What other switches are needed to make the blower blow?

Mucho thanks!!!!

[Pool Clown]

You will have to find out if it is the blower switch(fenwal or ignition control), or the blower itself.

You should get 110V between F2 and ground, with a call for heat.

[Bugman1400]

You will have to find out if it is the blower switch(fenwal or ignition control), or the blower itself.

You should get 110V between F2 and ground, with a call for heat.

For a 240V connected motor (L1 & L2), I am assuming that either L1 or L2 stays connected all the time and then a relay/contactor is switching in the other hot leg. Is this correct? Also, is this handled through the Ignition Control? Nevermind, I see from a Fenwal manual that F1 and F2 power the blower. I see the Ignition Control module...what is Fenwal? Nevermind, I figured out that Fenwal is the Ignition Controller. Also, for testing the blower, I had planned on disconnecting the terminals and bumping it with 240V to see if it spins. As I said before, I don't think it is the blower since I never got 240V across the terminals, but I'll check anyway.

Much thanks PC!

[Bugman1400]

When I initially tested F2 to Gnd I did get 120V. However, I think I was reading L1 through the motor winding. When I disconnected the BLACK motor wire I then got zero volts to Gnd on F2. I also confirmed that the blower motor is working; when I connected it directly to L1 and L2. I also confirmed that F1 to L1 is 240V. It appears that F1 is switched through a relay on the Fenwal board to source F2. This does not seem to be happening in my case. So, I am guessing that I have a bad Fenwal Ignition Control. Would you agree? Or, is there a signal sent from the Electronic Controller to tell the Fenwal to start the blower motor?

Thanks Pool Clown.

[Pool Clown]

You're kinda making this confusing. It's simple.

Disconnect the wire from F2 and see if you have 120 VAC at the terminal, not the wire.

When the fenwall switches, it just closes F1 & 2. F1 should always be hot, when the heater has voltage (pump on). Fenwall does get a signal to close F1 & 2 from control when there is a call for heat.

[Bugman1400]

You're kinda making this confusing. It's simple.

Disconnect the wire from F2 and see if you have 120 VAC at the terminal, not the wire.

When the fenwall switches, it just closes F1 & 2. F1 should always be hot, when the heater has voltage (pump on). Fenwall does get a signal to close F1 & 2 from control when there is a call for heat.

I disconnected the wire from F2 and get zero volts at the terminal. Sounds to me that my 05-33 Series Fenwal is bad. Would you agree? If so, is there a cheap replacement for these? The price I see on the internet are around $340....whew, that is high!

[Pool Clown]

That sounds about right, but look around on the web, you may find a better price here.

[Bugman1400]

That sounds about right, but look around on the web, you may find a better price here.

I almost bought a Fenwal on-line, but I made one last check to make sure that buying a new unit would not result in the same problem. After a bit more research on the schematic, it appears that the Fenwal is looking for a call for heat (24V) on the IND terminal from the controller. The inducer blower then starts up. It then expects (24V) on the TH terminal from the controller after the pressure switch does its thing. After that, I think the ignitor then glows. Well, I do not appear to be receiving any of the 24V from the controller. So, now I am to believe that the controller is bad. That's even more money!!!!!! However, I found a controller for an LX400 on E-bay for $170, but I have an LT400. The question of the day is......can I use the LX400 controller on the LT400?

[Pool Clown]

If the IND (wire) isn't getting voltage, it's because you're not getting a closed circuit from the safety switch group. Check the switches in that group: Pressure, fire, Hi limit 1 & 2, fuse link/Roll out, and exhaust limit temp switch.

Note: these are in three different groups that return to the control.

1.Pressure and fire switch,

2.Two (separate) hi limits

3.Fuse link/roll out with exhaust over temp.

Note: Fuse link is a one time blow. It will not reset, and must be replaced.

Call for heat relay separates/closes group 1 & 2.

Also, you're doing this with Pump on, and there is (good) pressure, and all switches are disconnected when testing them.

Hope all this makes sense.

[Bugman1400]

Thanks for the info. I will jumper accordingly and see if IND gets the 24V.

[Bugman1400]

Thanks for the info. I will jumper accordingly and see if IND gets the 24V.

Well, I got my heater working....sort of. I manually jumped 24V to the IND of the Fenwal, but the unit still would not light. I saw Pool Clown's advice on another thread about the flame sensor so, I passed the sandpaper over it a few times and it worked. So, now the heater will light with the 24V jumped to the IND terminal. Obviously, this is a bad way to do things since it bypasses all the safety switches, but at least I got confirmation that the Fenwal, gas valve, HSI, and blower works. I also checked all of the switch paths and they have continuity. This leads me to believe that the controller is bad. Luckily, I found a new one on E-bay for $160.

Mucho thanks PC...........You rock!

[Bugman1400]

Thanks for the info. I will jumper accordingly and see if IND gets the 24V.

Well, I got my heater working....sort of. I manually jumped 24V to the IND of the Fenwal, but the unit still would not light. I saw Pool Clown's advice on another thread about the flame sensor so, I passed the sandpaper over it a few times and it worked. So, now the heater will light with the 24V jumped to the IND terminal. Obviously, this is a bad way to do things since it bypasses all the safety switches, but at least I got confirmation that the Fenwal, gas valve, HSI, and blower works. I also checked all of the switch paths and they have continuity. This leads me to believe that the controller is bad. Luckily, I found a new one on E-bay for $160.

Mucho thanks PC...........You rock!

UPDATE: Went by the Rat Shack and bought a pack of jumpers and a 12-0-12V hobby xfmr and then bench tested my controller. Well....it worked as designed. I think one important thing I missed from the beginning of my ordeal was to listen to PC when he said to check the "3.Fuse link/roll out with exhaust over temp". With this circuit jumped out the controller works great.

[Pool Clown]

It's great that you found out what part was preventing joy.

Now you should find out (as you should with any type of safety switch), what caused it to open? When a over temp or roll out trips, it's not the kind of part that you just replace and go on your way. You NEED to find out why it opened, or you may be changing that switch again.

[Bugman1400]

It's great that you found out what part was preventing joy.

Now you should find out (as you should with any type of safety switch), what caused it to open? When a over temp or roll out trips, it's not the kind of part that you just replace and go on your way. You NEED to find out why it opened, or you may be changing that switch again.

UPDATE: The exhaust over-temp switch has a little red button on the back. Once I pressed that, I got continuity. Now, I am receiving the 24V signal to the IND terminal of the Fenwal. I'm not sure why the over-temp switch was tripped, but there are no other signs. When I picked up this used heater it was covered with leaves, sticks, muck, etc. Perhaps the exhaust got blocked at some point.

Thanks again!!

[Bugman1400]

Okay, got a question for all you LAARS pool heater repairmen.

I ordered a 150 deg HI-LIMIT switch and harness (R0334700) that goes with it and the 135 deg switch. The problem is that the wire between the two switches is too short and is also white versus the original black.

Any suggestions or tricks of the trade?

I'll curse the first person who tells me to paint the wires black!!!!!

IOW, is there a vendor that sells the correct harness or should I just forget it and fix the original harness.

Mucho grassyass and have a great weekend!!!!

[Pool Clown]

You can splice, or put a new longer wire in its place. Just make the splice bullet proof against the elements.

Or you can paint it...