It works fine for about 20 min.then it starts beeping and alarms ging off sometimes it stops for a few min and then it tarts again I can turn it off and back on and it does good for about 20 min is there a reset button somewhere I can't find

Just wondering if it needs a filter change or clean....these sometimes have a built in timer that counts the hours of use so that you know when to clean the filters.

Are you buying really cheap fuel, Mark? Try buying good brand-name fuel.

it could be a faulty blower motor.
You said AIR on hot or cold.... what about just vent on high with the AC off? does that work normally?

You might want to check and see if that was the right lamp for that tv. You might have the wrong lamp

may be motor switch or motor x

A Big hammer? or have you tried turning it off at the mains for about 15 - 20 mins then back on again that should reset it.
ThanksTalkAppliance.co.uk

Can you or somebody you know disconnect the alarm completely?

This happened to me, my smoke detector started chipping so I changed the batteries. A few seconds later it started chirping again. The answer is in the way you put the batteries in. The smoke detector allows you to put the batteries in wrong and makes a slight connector. This slight connector tricks the detector into thinking the batteries are weak. Simply turn the batteries around so the fat connector of the battery touches the skinny connector of the device. Mine was, fat side on the right.

one of the door or bonnet or boot switches is not working and its telling you it's not closed. if your interior lights are not on when you close the doors then it will be the boot or bonnet switch playing up. disconnect the wiring to the plug on the switch and you will find the faulty switch when you activate the alarm.