kjbro

Sorry to ask what seems to be a silly question, but I'm not sure of the proper way to run heater in my 95 LS400. My owner manual comments on the use of the A/C, which I relate to "air cooling" more than "climate control. When heating the interior, is it proper to have the A/C button illuminated? When I push the "auto" button and adjust the temp. to....say 85, the A/C button is on and the outside airflow is on. How do most people run their system to warm the interior. I've talked with a couple others who admit they don't really know and were embarrassed to ask. Thanks.

SW03ES

Yeah just leave it on auto and let the A/C light stay on and set the temperature as desired. The computer will make the decision to switch from air conditioning to heat based on what you select.

kjbro

Thanks SW03ES....will the A/C light go out after computer determines that heat is requested.

jimmit

I would think to use the heat you would probably turn the AC off. When I use my hea I dont use the AC. I keep it off. I get hotter air if I dont use the AC. Why use more gas and create heat when your engine produces more than enough of it that you can just use when you keep the AC light off.

kjbro

Jimmit, those were my thoughts as well. I have not owned a car that used this type of system. Seems we are still in question on the right way to use "heat mode". I will say, however, that the manual does leave me with the opinion that the A/C light is illuminated when requesting temperature change. This appears correct for both heating and cooling. Why would A/C run to heat interior above outside temperature? Or, is the A/C button not 100% "air cooling" but "automatic climate control"? Anyone else with thoughts or opinions?

SW03ES

If you want to use the automatic climate control function, then the A/C light will always be on. If you want to just dump straight heat into the cabin then you can turn the system on.

I've never found the heat in my dad's 98 lacking in Auto mode.

squarehat

My '96 ES does the same thing. I was told the A/C is used to help dry the air going to the front defogger, and that it supposedly just "cycles" the compressor when the heat is on (or its cool enough to cool the car with ambient air), to keep some seals in proper conditon. Supposedly, the A/C compressor cycling occasionally will not rob you of HP or fuel economy the way it would on a 95 degree day.
The climate control system seems very "clever", even knowing when to switch from dash to floor vents and re-circ/outside air. I would hope it would also keep the system from wasting HP and fuel.

SW03ES

Actually from what I understand the LS compressors do not cycle. I've always been under the understanding that there are two, one for each zone because of the two condensation puddles underneath the car.

kjbro

On my way home last night, I tried both methods. After car had been driven a bit, I turned on the "auto" button. The A/C button came on and I adjusted the temp. setting to 80. I started to fog a bit in the car, so I turned on the defrost (front and back). I didn't give this much time as fogging continued and I thought the windows would fully fog. Went back to A/C "off", outside air flow "on" and temp. at 80. Things warmed up and fog dissapaited. That experience led me to believe that "no" A/C is best, but maybe I didn't let the system cycle enough. This morning, I warmed car in the "no A/C" mode and the interior was toasty. My vote, today, is to use heating system without A/C. Will keep experimenting.

Disclaimer - I live in the "cold" region of Bay Area (Northern California), were the mornings can get in the mid 40's. I know I won't get much sympathy with this comment! Cheers

SW03ES

Don't know what to tell ya man. If no A/C works best, then no A/C works best

kjbro

I may be "Beating a Dead Horse". Read today in paper an article in "Auto" section about use of defrost. The article mentioned that if you have "Climate Control" type system, that you should use A/C when defrost (front window). Front window defrost is best with fresh air. Article went on to say that if driver wants heating in car while on defrost, just increase temp.