1991 240sx: idle drops 100 rpm when heater turned on

[RedtopTech]

it's actually the electrical load of the blower motor that drops the rpm. Turning on the headlamps at idle will produce the same effect. It's not really an issue, most late model and many newer cars do this. Just make sure you have a good charging system.

[nixad]

postlenght

[surreybc]

Originally Posted by RedtopTech

it's actually the electrical load of the blower motor that drops the rpm. Turning on the headlamps at idle will produce the same effect. It's not really an issue, most late model and many newer cars do this. Just make sure you have a good charging system.

ok. i'll have to check the amps for the blower. I never thought of it as placing much demand on electrical system. Also, I thought that the idle is supposed to go up to compensate for increased electrical loads. My lights lower the rpm about 50 rpm.

Im trying to figure out why my idle plummets to around 500 on cold days when I push clutch in. It plummets quite a bit less when the heater fan motor is off. Ill have to try a new iacv.