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The AMM can suffer from constant overheat if you have:
- the preheater hose connected between the exhaust manifold heat shield plate and the bottom of the air filter box (under the fan shroud)
- not replaced the inside the air filter box flap valve springy thermostat every so often (how often?). The flap valve inside the air filter box, because of the springy thermostat fails in time, gets stuck on "let in the hot air all the time" which will fry the AMM in a summer or two or less. (The LH-3.1 AMM may be somewhat more robust, though will fail, too. An expensive item to replace, the AMM.)
Though you'll test you AMM as others are directing you to do so with your new multimeter.
Images shows the silver preheat hose, though the image is of the older exhaust shield.
Flushing, New York can get really hot during heat waves. Coupled with hot air from under the exhaust manifold heat shield, the AMM becomes a well fried crispy of an AMM.
See this yoo bube toob video shows the action of the cold air / hot air control air intake of the inside-the-air-filter-box flapper valve:
https://youtu.be/FGWXXyXD2ME
I don't know the emissions inspection requirements for NY-state, though I read it is stricter than most states. CA-state requires a visual inspection of emissions controls. You cannot remove that silver preheat hose to pass emissions (smog) inspection.
You can buy a replacement thermostat so your air filter flapper valve works.
Volvo OEM part number (PN) 1266826. Wahler (PN) 70411.
You can purchase replacement (prices without shipping - local parts store may be an option):
Tasca Volvo in Cranston, Rhode Island for 47$ (May or may not be made by Wahler, no image):
http://www.tascaparts.com/?p=catalog&mode=search&search_in=all&search_str=Volvo%201266826
FCP Euro in Groton, CT for 10$:
https://www.fcpeuro.com/products/volvo-engine-air-box-thermostat-1266826
iPd USA in Portland, OR for 13$
https://www.ipdusa.com/products/5451/103083-airbox-thermostat-valve
So, you replace the air filter box warm air control flapper valve thermostat every so often (how often?). Wahler is (or was) OEM, like your coolant thermostat, so you can purchase replacement. Wahler is now owned by Borg-Warner in Germany. Though where Whaler has this thermostat manufactured is unknown. I dunno how long these new part would last.
MO, CO, WA, and some other states do not perform an emission inspection. So, I removed the silver accordion hose and saved it. When in CA-state, I plugged the arm air inlet and mechanically forced the flap valve to remain on cold air open. Though in MO, on my 1992, I removed the flapper valve assembly and stored it, and the engine draws air through both air inlet ports on the filter box.
I'd replaced this part a few times when I needed to on my 240s. Though replacements do fail, I found.
Questions? Hope that helps.
MacDuffed.
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