On Tuesday, July 31, 2018 at 8:26:55 AM UTC-5, N_Cook wrote:
Intermittant failure to heat.
Not due to failing switch, but original plastic stress-relief sheathing
at the blue body gone hard with age and causing stress to cable and then
a conductor break. Makes you wonder where all that plasticiser migrates
to, presumably us , quite a bit.

It outgasses..... to atmosphere. Just like the buildup of haze on the inside of your windshield after a hot summer. That's your dashboard, vinyl, carpeting, wire insulation, powder coated parts, upholstery, foam, virtually everything in your car's interior except the metal itself, condensing on the glass and every other surface. Good reason to keep the air flowing thru the vehicle as you drive, minimize the inhalation of those compounds. Gotta love that new car smell.