My AC has not worked for a couple years now and I have taken it in to my mechanic recently and he is telling me I need a EVP valve replaced and he said he got a price from lexus for about $800.00 but i cannot find any information whatsoever on this part online, have you ever heard of it?

David,
DTC 3-4 at idle means the EVP voltage is above the closed limit.
Translation: The EVP sensor (EGR valve position) is unplugged or the wiring between it and the computer has an open. The EVP sensor has a 3-wire plug on it, and you can find the EVP on top of the EGR valve (that's the metal mushroom between the intake and a pipe coming from the driver side exhaust manifold (on a v-8)).
It's also possible that the EVP sensor is bad (open).
Good luck.
Mike M, 35-year Phord Phixer

So your telling us you need a mechanic-- again

Can't guess-- to give you an answer,you knew that

Vehicles have to be tested to find problems

Kia Sedona expansion FRONT valve located under dash, behind glove box, fan and coil. Evacuate freon first. Disconnect Freon lines from firewall., Lay right front seat back to flat horizontal position and lay on top or totally remove the seat for easier working access. Remove under dash cover, fan, glove box, coil housing, remove coil mounting bolts, remove old expansion valve. (Inspect old valve, if debris inside, blow out coil before installing new valve. If visible debris best to consider replacing REAR expansion valve and DRIER/FILTER in front of radiator too and blow out all lines and coils while servicing.) Use compressor oil to lubricate "O" rings on new FRONT or REAR expansion valve, install valve bolts, reinstall coil bolts to FRONT firewall or REAR frame, reconnect freon lines to firewall in engine compartment. Evacuate AC system, install freon (35 1/2 ounces, nominal 3 pounds), check system for leaks, check for proper operation, enjoy.

In the two years since it last worked the gas pressure could have fallen so now it won't work and wouldn't have worked if you hadn't borrowed the relay.

On average a vehicle air-con needs a top up every couple of years so I suggest you begin by visiting your local air-con service centre.

Instead of the marvel oil I would change the oil and filter and add one quart of Lucas oil additive as it will help coat the cylinder walls and reduce the oil consumption. You may also want to replace the PCV valve on top of the valve cover as a sticky PCV valve could be causing internal pressure to build up in the engine and cause oil to leak past the piston rings.

If it is not the freon, then it could be the electronics that are supposed to electrically open the valve that lets the freon into the evaporator that gets cold. It is not a pressure sensor, but a valve.

But yes, it is easy to replace the airbag sensor in the bumper.
Here is a site with all the info, for each model, make, and year.
http://www.airbagsolutions.com/

sounds like you need to take it back to the mechanic and tell him this. then tell him to fix it correctly or pay for another shop to fix the problem. it seems that he is not getting it bleed correctly.

Hi,

HOW TO INSPECT EGR VALVE

Before attempting to troubleshoot or repair a suspected exhaust gas recirculation (EGR) system on a vehicle, the following conditions should be checked and be within specifications.

• Engine is mechanically sound.
• Injection system is operating properly.
• Mechanical-vacuum advance is properly adjusted or the electronic advance system is operating properly.

If one or more of these conditions is faulty or operating incorrectly, perform the necessary tests and services to correct the problem before servicing the EGR system.




Before attempting any tests of the EGR system, visually inspect the condition of all vacuum hoses for kinks, bends, cracks, and flexibility. Replace defective hoses as required. Check vacuum hose routing. (See the underhood decal or the manufacturer's service manual for correct routing.) Correct any misrouted hoses. If the emissions system if fitted with an exhaust-gas-recirculation valve position (EVP) sensor, the wires routed to it should also be checked.
If the EGR valve remains open at idle and low engine speed, the idle operation is rough and surging occurs at low speeds. When this problem is present, the engine may hesitate on low-speed acceleration or stall after deceleration or after a cold start. If the EGR valve does not open, engine detonation occurs. When a defect occurs in the EGR system, a diagnostic trouble code (DTC) is usually set in the powertrain control module (PCM) memory.

Cont....

had same problem had to replace the compressor about 800.00 dollars .