2 Problems

[BillyC]

I'm down to just 2 problems on my 91 LS400, and would appreciate your opinions.

1. The check engine light comes on, stays on for awhile, and then goes off again. There is no difference in the engine performance with the light on or off. In fact, on a recent trip I got my best mileage ever, 26-27 miles per gallon with the check engine light on most of the time. Any idea what is going on?

2. Sometimes the air conditioner cools, sometimes it doesn't. I had the system evacuated and refilled to the proper amount with R-12 refrigerant. No change. When it is cooling properly, the air is really cold, but most of the time the air is just cooled a little. What is there in the system that could cause this kind of intermittent operation?

Thanks,

BillyC

91LS400

216,000 miles

[blake918]

When it is cooling properly, the air is really cold, but most of the time the air is just cooled a little.  What is there in the system that could cause this kind of intermittent operation?

For the cel, you need to retireve the code and post it on here.

Do you use the "Auto" feature on the A/C controls. I thought my car had a similar problem until I found out that the auto controls the actual temp of the air and the speed at which it comes out(I felt all different kinds of stupid!). Manually set the a/c on max cool and see how it feels. It's a stretch, but it's worth a try!

[V-10]

You might check the interior cabin filter for the A/C issue. My 95 couldn't keep up in the heat of summer and when I checked the filter it looked like a rats nest. Popped in a new one and it was like night and day.

Best

Steve

[wwest]

Just suppose...

Your mixture is running a bit lean..

The engine tends to overheat slighltly but only to the point of disabling the A/C and an engine diagnostic indication.

[chazglenn3]

You might check the interior cabin filter for the A/C issue. My 95 couldn't keep up in the heat of summer and when I checked the filter it looked like a rats nest. Popped in a new one and it was like night and day.

Best

Steve

No cabin air filter on the 1991 LS400. These didn't appear until 1993.