Quote:
Originally Posted by TyzToyz
Hey all,
With the warmer weather here I fired up the A/C for the first time. At first it was cool but not cold, so I recharged the system (first time), and it blows cold now but when the compressor kicks in the idle drops to 400rpm (almost but doesn't stall).
Is there a separate idle up adjust screw (like on a 22RE) for the A/C that I can adjust without affecting the regular idle?
Tye
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Is there a separate idle up adjust screw (like on a 22RE) for the A/C that I can adjust without affecting the regular idle?
The answer to that question is no.
There is a valve mounted on the firewall between the MAP sensor and the wiper motor that Toyota calls a VSV valve that is responsible for increasing the idle to between 900 and 1100 RPM when the A/C compressor kicks on. This valve has a two wire connector on it and two vacuum lines go from this valve to the intake manifold. It is held to the firewall just next to the windshield wiper motor with one bolt that takes a 10MM socket to remove it. Do not confuse the VSV valve with the MAP sensor which only has one vacuum line going to it. Most likely you have a bad VSV valve. You can test the valve by measuring the resistance across the tabs where the electrical connector attaches. You should have between 37 and 44 ohms at 68 degrees F, but I've seen them function properly with 65 to 70 ohms at 68 degrees F. Also, while you have your ohm meter out, you want to make sure each tab is not internally grounded to the case. Also you want to confirm there is not an open circuit (infinite resistance) indicated across the two tabs. If there is, the VSV valve is definitely bad.
The only other thing that could be the problem, but not likely, is a bad A/C amplifier which is located up under the passenger's side dashboard, above the plastic box that houses the heater core and A/C evaperator, but failure rates on those are very low.
Most likely if you swap out the VSV valve with a good one from the junkyard, you will be good to go.
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