Fogging Gauges

Yesterday, while driving in the hot humid Florida weather with the A/C at full blast, I noticed that the fuel/oel and temperature/pressure gauges were accumulating condensation on the inside of the glass. The temp/pressure gauge was the worst and almost got to the point where the readings were hard to make out. Does anybody know what might be causing this problem? Is there a seal that might not be working right? Thanks in advance for any insights.

Ruben
1976 911s

This is common. Your AC vent runs behind the gauges and cools them from the back. The warm air on the outside the condenses on the glass gauges and fogs. It is a sign that your AC is blowing very cold.

My car doesn't have A/C and my fuel/oil gauge gets fogged up in the Winter and sometimes in the Summer when it's foggy. It goes away after a while though.

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Zach
77 911S 3.2

Same here, I pulled out my gauge to see if there was anything I could seal up but I had no luck.
Only happens in the winter though.

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Leland Pate

___79 SC Targa

Some people I know have put Sodium Silicate (the small packs contained in electronics packaging for moisture absorption) inside their gauges or taped at the back of the gauges. The unknown are how long it takes before the stuff is saturated, and there is little room inside the gauge for the bags.
The moisture doesn't bother me, and I've noticed that putting the lights on (i.e. lighting the gauges reduces the amount of fogging and sometimes makes it disappear. Probably the heat from the bulbs?
My $0.02, GeorgeK

The proper fix for this problem is to remove the offending gauges and drill a small hole in the rear bottom of the gauge housing. This will allow the humid air to escape. It also helps if you place some fiberglass insulation behind the gauges help combat the temperature drop in the gauges from front to back.

Good Luck,
Lee Wister