Water Pump indicated as reason for A/C problems

2006 Lexus IS 350, 100K miles, A/C runs cold then runs warm. Dealership told me they would perform a/c pressure & leak test for about $170. after a few days I would return and they would check for leaks.

Instead, they said they found coolant leak around water pump and recommended water pump replacement for $1200. A/C has been operating intermittently for 2 seasons, but never any indication of water pump problems. I declined repairs since I was surprised at the diagnosis and stunned at the price. The technician advised water pump problems could occur even though none had been previously experienced.

Drove 45-60 minutes home with no problem. The next time I drove the car was 4 days later and, sure enough after about 45 minutes and miles from home the engine light and vsc light came on and there was noticeable vibration. It took me 90 minutes to creep home at 20-30 mph and I smelled coolant.

I hate to accuse, but I don’t think anything was wrong with my water pump til the dealership messed with it, and how do I know replacing the water pump will fix the A/C problem if the pressure & dye test was not performed.

What do you recommend as next steps. I don’t want to go back to Lexus. Is it OK to drive the car about 6 miles to a neighborhood Goodyear car repair shop and get another estimate?


A water pump can not be messed with by the dealer. It will not fix your ac problem. The overheat problem is the major problem now. Hopefully your engine is not hurt. Take it to an independent mechanic listed in the mechanics files above.

The intermittent AC operation might be caused by a failing expansion valve.


The expansion valve is what converts the high pressure liquid into a low pressure gas at the evaporator which creates the cooling effect.

One of the indications of a failing expansion valve is, the AC cools fine for a period, and then stops cooling.

Since some of the refrigerant lines need to be removed in order to replace the water pump, replacing the expansion valve at this time would be cost effective.


It appears you’ve got two separate problems. The most important to address promptly is the water pump. It’s not at all unusual for a water pump to fail on a 2006 at 100K miles. And I expect $1200 is what it costs to fix a Lexus water pump at a dealership. In fact that is less than I’d expect for the quote. Replacing your water pump at an inde shop might be a little less expensive. To find a good local inde shop, ask friends, co-workers, fellow church goers etc who they use.

As with many vehicles the engine controler will disable the A/C compressor when the engine is running hot, usually 10F below boil over. I have had many customers complain about the A/C shuting off but say nothing about running hot/lack of coolant, which was the real problem.

If you didn’t trust them you should have looked at the leak yourself while they had the covers off. Perhaps if you were convinced that it was leaking you would have had it towed to another shop rather than driving it.

The OEM water pump is $210, coolant $60, labor 3.6 hours. This would come to about $900 with shop supplies and tax at a dealer. If you think that is expensive you’ll be shocked when you find out what it will cost to replace the engine.

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Really appreciate all comments. Just concerned that water pump problem may have resulted from connections that may not have been re-tightened properly after I declined repairs. And, btw, Lexus dealer also passed the car for state inspection during same visit.

The water pump is bolted firmly to the engine. All the dealership did was notice coolant seeping from the gasket at the base of the water pump. They did not disconnect/reconnect anything except a plastic cover. After that, they simply used their eyeballs.

The water pump was leaking before you reached the dealership, and it was leaking after you left the dealership. When they told you the pump was leaking, you should have asked to see the leak and recognized that they were telling you the truth and had the water pump replaced.

Yes, it’s good to be skeptical. But when someone tells you something critical is wrong with your engine, it’s best to take it seriously and try to verify the claim yourself and not just assume they are lying.

Repairpal.com gives an estimate of $600-$800 for the water pump replacement. High end is the dealership rate; you should be able to get a better price from an independent or chain shop.