They won't run if it's stuck open. Thermostats open and close as the engine temperature dictates. The idea is to keep the engine running within an "ideal" temperature range. Mike -----Original Message----- From: Martin Gutkowski [mailto:webmaster@xxxx] Sent: Wednesday, January 23, 2002 5:05 PM To: dmcnews@xxxxxxxxxxxxxxx Subject: Re: [DML] too cool cooling, stuck thermostat?! Surely if the thermostat was stuck the fans would run non-stop? Do they cut in and out properly?