The "resistor" is a metal box with wire coils; it sits on the passenger (right) side inner fender. Although anything can break, I've not heard of any actually doing so. The climate control problems that get the most play here are
(a) resoldering or replacing the pushbutton control unit,
(b) rebuilding or replacing the monovalve,
(c) rebuilding or replacing the auxiliary water pump (remember to add a fuse),
(d) replacing the brushes in the fan motor or replacing the entire motor (my brushes had worn into the commutator so much that I had to replace the motor),
(e) replacing the disintegrated foam tube that connects the interior temp sensor to the blower intake, and
(f) rebuilding, replacing, or working around failed vacuum pods (that move the doors to direct air here and there).

This does not count repairs to the refrigeration system, which can be a whole set of problems by itself, nor does it cover bad thermostats, clogged radiators and heater cores, and other parts of the engine coolant plumbing.

Mercedes designed the climate control system to default to "hot air to the windshield" as a safety measure, so you could always get your windshield clear of moisture, ice, etc. If you have a problem where that occurs sometimes but not always, the electronics are probably getting flakey. Someone here probably has had that exact problem and can tell you what to do.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970