Forgot to answer. No, I don't have a blower.

There is porbably still a blower circuit, check it, it shuts off the heat.

I don't believe there is a blower circuit on my control pack. The pack is close to the right side of the compartment, so I couldn't look at the plug straight on. The top plug is labeled pump 1 and the next plug down is labeled blower. I noticed the color of the wired on the pump plug, and tried to test the plug marked blower accordinly.

I got no reading on the blower plug, no matter what I did. To verify, I pulled the pump plug and tested. I got one hot in circulation mode, and the other hot in jet mode. I didn't think to test if both were hot in jet mode, and I suppose it doesn't really matter. There are only two air switches on my control pack. One is connected to the Jets air button and the other is connected to the Lights air buttton. It was getting dark by the time I got home, so I didn't get a chance to open the control pack.

There is a rocker switch above the timer on my control pack. One side is labeled Timer, and the other is labeled Auto. When the switch is in Timer mode the, the pump on works in circuation mode when the timer is at the set time. If I flip the switch to Auto, the pump runs in circuation mode. If I turn the thermostat switch down to warm, the pump and the Heat light
goes off and the Ready light comes on. If I turn the thermostat switch up toward Hot, the Ready light goes out, the pump comes on in circulation mode and the Heat light goes on. As near as I can tell the Heat light is on as long as the actual temperature is lower than the setting on the thermostat switch, regardless of what is on or what mode the control pack is on.

I noticed that my control pack is a Hydro-quip DS2, and not a DS-1.

Set the switch to Auto, then it will heat acording to the t-stat setting, in Timer it will only heat during the "time" cycle.

I fixed it! After scratching my head for about a week, my wife finally mentioned that she had been resetting the high temp limit switch. Every time I checked it the switch was set correctly, but she usually gets home a hour before I do.

I did a little more troubleshooting and decided that the high temp limit switch was my problem. I did some research on the Internet and then removed the switch from the control pack. I adjusted the switch and re-installed it. The heater now works fine. During testing, I had the tub up as high as 105, but it is now down to 102.

The tub has been running great for about three weeks now. I have it running on the timer for two hours each day. With the insulated cover, the temperature is always right where it's set on the topside control.

WARNING: The high temp limit switch is an integral safety feature. Do not attempt to modify or adjust this part yourself. If you suspect that you are having trouble with your high temp limit switch, consult a professional hot tub repair company.

Thanks everyone for your comments and suggestions. The wife and I are now enjoying the tub. We're pretty proud of our $385 investment (not including installation costs of course).