Arkberry how large is your greenhouse? I have a 6x8 greenhouse and I find a fan for air circulation a must , circulates the warm air from the top of greenhouse to ground level . Plants do so much better with air circulation, I guess it kind of mocks conditions in the real world outside of the greenhouse.Unless you have a massive greenhouse a small portable heater is a must for cold nights like you guys have been having. If your greenhouse is small all you will need is a small 1500w heater for the nights.Speaking of cold going to minus 4 in the next coming nights.

I got tired of all the hours I spent each year trying to find which bulbs were defective. I finally got a gizmo called a Lightkeeper Pro and it helps a lot. Bulbs typically have a bypass built into each one which is supposed to pass the current on even if the bulb fails. However, this does not always work, and then you have a bunch of lights out and you aren't sure what has actually failed. The Lightkeeper passes a small current through the lights and usually succeeds in activating the failed bypass. Then you can see which bulb or bulbs doesn't work and replace just those. Below is a link so you can see what this actually does. It has gotten a lot of positive reviews on Amazon, and I think you can buy it for less than $20. That's a little pricey, but it can save lots of time. Here is a link that might be useful: Lightkeeper Pro Video

well, by removing some lights, you could actually be making the others brighter. i have a few strands that if you remove more than 1-2 lights, the strand gets real bright! light strands are series-parallel circuits that are setup so that each bulb basically gets 1.5 to2.5 volts across it, depending on the exact setup of the strand. by removing bulbs, you change the ciruit resistance, and up the voltage to each bulb. as this happens, the bulb gets brighter and gives off more heat. remove enough and the circuit is broken completely on most stradns and you get no light. also, you say unscrewing the bulbs, so i take it this is not the mini lights but the older 4 or 9 watt screw in bulbs. they will produce much more heat than the smaller bulbs. as configured from the manufacturer, the bulbs should be safe. of course we all know that chinese crap may not be, but if the bulbs run cooler with all bulbs in, then i would leave it alone.

I'd check the output of the pedal switch with a voltmeter.