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Leak Tester Needed To Find Source of Air `Evaporation'

By Junior Damato, June 26th, 2010

strong>Dear Doctor: I own a 2000 Jeep Cherokee Sport and I'm having a problem with the R134a leaking. I had repaired the air conditioning evaporator core and dryer, but the a/c charge only lasts a short time. I cannot see any tracer dye leaking. The local shop tested for leaks and cannot find any. Any suggestions would be appreciated. Pat

strong>Dear Pat: You mentioned you repaired the evaporator core. There is no mention of replacement. If the system has dye in it and you cannot see any dye on the condenser, lines or compressor, then the evaporator box has to be inspected. The R134a does not evaporate, it is leaking out. Most shops will have a digital leak tester with a small wand. The wand should be able to enter the drain tube on the heater box. I sometimes will make a small hole on the heater box case to test for an evaporator leak. There are companies that sell a/c leak sealers. In some cases they do work.

strong>Dear Doctor: I own a 2008 Pontiac G8. The problem is the brake lights stay on. I installed a new brake light switch, but still have the problem. I thought the new switch was defective, so I replaced it with another new switch. The brake lights remain on. What's the problem? Randy

strong>Dear Randy: In the old days you would think the problem was a faulty brake light switch. With today's newer vehicles, however, whenever there is an electrical problem a scan tool needs to be used to check for any codes in the circuit. In your case, a check of the body control module is required. A misadjusted brake position sensor will also cause the brake lights to stay on. To recalibrate the sensor, a Tech 2 scan tool is required. At our shop we have most of the factory scan tools. It is expensive to own these factory scan tools.

strong>Dear Doctor: In 2000 I purchased a new Buick. It was recalled for a coolant leak and fixed under warranty. The engine is loosing coolant again. My mechanic pressure-tested the cooling system, but cannot find any leaks. What do you think? Fred

strong>Dear Fred: A cooling system pressure test is very good for locating external leaks, however, seldom will it reveal internal leaks, such as cylinder head and head gasket leaks. Have your mechanic buy a package of GM coolant pellets (stop leak pellets). These pellets really do work at stopping small internal coolant leaks.

strong>Dear Doctor: We have a handicapped family member and purchased a 2001 Dodge Caravan Sport. It was converted by the Braun Corp. to a wheelchair-accessible, lowered-floor conversion. There is a problem with the electrical system. When the van is parked and the keys removed, the headlights, parking lights and fog lamps come on and stay on for several seconds (about 15-30 seconds) and then go off by themselves. The dealer replaced the battery three times. We brought it to an independent garage. They could find nothing wrong either, except the battery was dead and had to be replaced, again. We thought it might have been the headlamp module. What do you advise? Storm

strong>Dear Storm: The headlights and other accessories go through a body control module. It's not just a simple headlight switch to the headlights. There could be something else draining the battery, not just the headlight issue. You might give consideration to having a small battery maintainer connected and plugged into a house outlet. I use a battery maintainer in all our vehicles to keep the batteries charged. Seldom use and short drives will wear a battery down. Call Identifix 1-800-288-6210 and ask them for a knowledgeable repair shop in your area. You can also call your local AAA office for an approved shop.

strong>Dear Doctor: Recently, I saw an advertisement for the Cadillac CTS Sport Wagon V-6. Is this car just another GM car with different sheet metal or a real Cadillac? Have you driven the CTS? Benjamin

strong>Dear Benjamin: The 2010 CTS Sport Wagon is a real Cadillac, not just another GM model with different sheet metal. Our test vehicle was a rear-wheel-drive model. Look for an all-wheel-drive and the popular V Series 556-horsepower version as well. The Sport Wagon 304-hp V-6 packs ample power combined with the 6-speed automatic transmissions with driver control or sport mode. Or test wagon also had the 19-inch summer tires with polished alloy rims. It gets about 18/27 mpg on unleaded gas. The quality is built in every aspect of the CTS -- and it shows.

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