heater question

[steelman86]

when i run my heater on high after about 30 mins the blower quits working. when i checked under the hood my air condition hoses and such had ice all over them what the hay is going on?

[BlazerLT]

Whta setting are you using, defrost?

The fan on high or do you mean the temperature at max heat.

Please be more specific.

[steelman86]

when I have the defrost on high. after about 30 minutes it quits blowing. thats when the air condition lines have ice all over them, weird

[BlazerLT]

Because the defrost circuit uses the air conditioning system to dehumidify the air.

Do you have the fan on high as well?

[steelman86]

[yes

[BlazerLT]

Well, the frost is probably from the AC system dehumidifying the air.

Don't use defrost unless you need it. It really hurts your fuel economy. Don't use blend either. Once the truck is warmed up, use the vent or floor option.

The fan itself could be overheating and stopping or your relay for the max fan setting could be the problem.

[reddog654]

common problem with a/c's. As with most vehicles defrost activates your compressor (clutch) which in turn starts to circulate your freon which dries the air that defrosts your windshield(air dryer). Works the same when you have your a/c on clutch engages circulates the freon. when a vehicle is low on freon it can cause the line to freeze and show signs of ice. this is the best probability. A system that is over charged can also do the same thing(freeze the lines). Some people think the more freon the colder the air(not true).check your freon levels at once to see if you are low or over charged. Too much freon causes more friction which makes the high pressure rise and the freon can not circulate the way it is suppost to thus resulting in the line freezing. Not having enough freon causes the sysyem to work harder thus rising the high pressure making the system work harder high pressure causes the freon to slow circulation thus resulting in the low pressure line to freeze. Sorry for going into so much detail people need to know how it works so they can understand better. When you have the proper level of freon your low pressure line(smaller than the high pressure line), you will see condisation on the line not ice. If you see condensation on the lines usually during the summer months then you are within the parameters. the compressor does not cycle as much when on defrost as it does when you have your a/c on. Do that and e-mail me with the results. [email protected]

[tom3]

I'd guess you have a bad pressure switch in the AC system, compressor should run for only a few seconds in cold weather. For now, might just unplug the connector on the compressor and disable it. Heat and defrost will still work. Need to have it checked out before summer though.