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Heat Only Part Time


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OK, here is the deal. Even though my 1995 SC400 is completely warmed up, the heater blower will not turn on until I start driving. Then it fires up and the air is warm. If I come to a stop light and stop, it then starts blowing cold. I already replaced the heater control valve and still the same problem. I inspected the vacuum hoses going to the heater control valve and they look OK. I also did a quick test of the the little check valve on the vacuum hose going to the heater control valve. Anyone had this problem before?? Any advice??

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Today I am going to add a little anti-freeze, just to top it off (the guy at Lexus and on this website said that might be the problem?. If that doesn't work, I am going to replace all vacuum hoses and that check valve leading up to the heater control valve.

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My '93 has done this for the past several years. Living in Houston, it really hasnt been a priority, but I'll have to try that. Though, I dont understand how that would fix the problem. Does anyone understand how exactly this works. Water or anti-freeze in the over-flow container isnt really being used... is it? I've also notice that, with my car, this problem comes and goes. Let us know if this problem resurfaces.

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OK, here is the deal.  Even though my 1995 SC400 is completely warmed up, the heater blower will not turn on until I start driving.  Then it fires up and the air is warm.  If I come to a stop light and stop, it then starts blowing cold.  I already replaced the heater control valve and still the same problem.  I inspected the vacuum hoses going to the heater control valve and they look OK.  I also did a quick test of the the little check valve on the vacuum hose going to the heater control valve.  Anyone had this problem before??  Any advice??

also check ur thermostat

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