If it is the same as the one in the '85 300D (W123), it is a common failure point. My '85 had a bad one when I got it; the PO had butchered in an ice cube relay so the a/c would work but with all of the "safeties" off. I suppose returning it or not depends on how badly you want the ($85?) money in your pocket versus having no a/c for a week while you buy another.

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"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