I can't remembar the exact reading but the heater should give a value like 9.7 or 12.2 ohms or something like that.

The relay to check voltage is the one that the heater wires attach to. If it's bad then you would need to replace that whole left side heater relay board.

Dan,

I checked the voltage at the terminals for the heater and have 246 there while the "heater on" light on the main board is on. After a couple of minutes there's a click and the "heater on" light goes out and the voltage to the heater goes to zero.

I metered the heater and got about 9.8 ohms, so that sounds like it is in the ballpark.

There seems to be flow thru the heater and the silent flow pump is running. If I pull the hose off the outlet there is a pretty good stream of water.

Any other ideas?

Check circ pump flow where it returns to the tub at the fitting that doubles as the drain grille.

The pump can be "running" while not flowing. Be sure your filters are clean as well.

summer timer is engaged, turn it off.

Don't think the heater keeps running for two minutes if summer timer is engaged. The circ pump does, but pretty sure the heater doesn't.

Thanks to all for the replies. I've checked the filters and also tried it briefly without them in place...the heater still trips after a minute or two. There seems to be flow at the drain. As I hadn't really noticed the flow rate before, I have no idea if it is normaly or not. SHouldn't I get some error indication if it trips the heater due to low flow?

I've verified it is not in summer mode.

I've replaced both thermistors as they appeared to be very slightly out of spec. This made no difference. There are no blinking lights or other indicators that something has tripped, other than the heater on light on the main board going out.

As an experiment I bypassed the heater realy board and ran power directly to the heater. The tub seemed to warm up normally.

Any ideas? Is there a way to trouble shoot the ciruit boards? (without just buying & substitution?)

Thanks,

Ken

You've done most all the troubleshooting I can think of. Sounds like a new IQ2020 box is needed. Sure there is no "SUN" icon on the upper right side where the temperature reads?

This is going to sound weird, but if the spa is equipped with an auxiliary control, unplug it.

It looks like a phone cord, and plugs into the IQ2020. One of the symptoms of failure will cause the spa not to heat.

If that doesn't fix it, flip a coin, could either be the IQ2020 or control head.

If it gets to that point, personally, I'd try plugging a new control head before replacing the IQ2020. Just much quicker, and no time loss if it's not the problem. You'll only burn a few minutes replacing the IQ2020, but if it turn out to be the control head, well, those are lost minutes.

i own a 1999 landmark w/the iq2000 board
my hottub started tripping off after attaining the target temp (104*) for about 2 days, starting last year. We had the HotSprings tech guy come out late Sept this year to trouble shoot it, along with reading up on it on this board. He determined the control head board was defective, along with the ozinator being dead. He replaced both and left.
The problem I now had was the tub would not heat for more than 10 minutes without the heater tripping off. The problem was worse!
Well the next step was replacing the thermosisters, which did not work. The next step was to replace the circulation pump, which also did not cure the problem.
We then (we thought) isolated it to the thermodisc high temp limit switch that sits on top of the nofault heater, which is reset manually with the little red button. We replaced it, which again did not solve the problem. We even removed the thermodisc switch and shorted the connection, but the heater kept tripping off.
pretty frustrating.
I finally got ahold of a "senior" tech man, who said that some of the new style ozinators are emitting a RF signal that interferes with the main circuit board and causes the heater to trip offline!
I unplugged the ozinator, and viola!, the tub heated for a few hours and now is at 104* and operating normally.
The tech said to wrap the ozinator in aluminum foil to kill the RF signal, but I think I'll have them replace the one in the tub under warranty.

hope this helps.