Coolant comes out of A/C condensation drip tube...any ideas what's wrong?

[93_Previa]

Yesterday our 93 Previa had what looks to be engine coolant dripping out of the A/C condensation drip tube (the tube that hangs down underneath the vehicle and drains what should only be condensation/water from running the A/C). I had checked the engine coolant level 1.5 weeks ago and everything checked out, but then yesterday my wife noticed something amiss dribbling from the A/C condensation drip tube. We took it to an Xpress lube place and the tech there said it was engine coolant, based on the taste and appearance. The engine coolant level had definitely dropped during that time yesterday, so I'm almost 100% convinced it's engine coolant coming out based on the taste/appearance/lowering of the engine coolant level. Thankfully the engine temp never went up, as my wife caught it in time!!!

From my limited knowledge, the only way engine coolant is going to be coming out of the A/C condensation drip tube is either a bad (leaking) heater core, or maybe some valve that's stuck open?? I can't figure out where engine coolant would come in touch with the A/C condensation drip tube???

We have it at a mechanic right now to diagnose it, but after doing some research on this site I couldn't find anyone having an issue with coolant coming out of the A/C condensation drip tube.

Tim, I found your very helpful Previa heater core replacement 'cheater' version (see: http://www.toyotavantech.com/forum/s...-a-heater-core ), but I'm still not 100% convinced it's the heater core. I don't want to replace it if it doesn't need to be replaced!

Any ideas?

[timsrv]

The heater core is mounted in the same "suitcase" as the AC evaporator and is the only potential source of coolant dripping from that area, so I would say it's gotta be your heater core. I've had one of my Previas get a heater core leak, but in my case it dripped onto the passenger floor and I could smell it at times (I never noticed it dripping out the AC drain tube). Good luck with getting things sorted out. Tim

[93_Previa]

Well, the mechanic we took it to is 95% sure it's the heater core as well. Although he is not willing to work on it due to its 'uniqueness'. And with your statement Tim about the only source of engine coolant in that area is the heater core it sounds like it's a clogged or leaking heater core.

Does anyone have any recommendations as to whether to go with a no-name aftermarket $50-$100 heater core, or whether to drop $250-$300 for an OEM heater core (yikes)? I'm not sure who the OEM is for the heater cores in these...I can't figure it out (Denso?, etc.?).

And Tim, the heater core replacement you did on yours...what year was your Previa that you fixed? In other words, we have a 93 Previa, so we do not have an airbag on the passenger side and I was wondering if that affects whether we can remove the plastic interior of the glove box, or whether we need to resort to heating it up and "reforming" it to gain enough clearance to get the heater core itself out like you did on your "cheater" heater core how-to that I linked to earlier.

Thanks for all the help!!

[timsrv]

The Previa in that write-up was a 91. The dash & glove box area on yours should be the same. When I did mine I used a salvage yard heater core. These are a PITA to pull though, so if I did it again, I'd probably go aftermarket. For parts like this, I wouldn't worry too much about brand, especially if you trim the nipples (like I did). Considering age and worth of these vehicles, it just makes sense to do the "cheater's way". No way was I willing to give up my whole day pulling the entire dash and suitcase out for a van that I paid $150 for. Tim

[93_Previa]

Just wanted to give an update for those who may be facing the same issue that I did with engine coolant mysteriously finding its way out of the A/C evaporator's drain tube, as well as onto our Previa's carpeted floor. And yes, we did confirm that it was the heater core that was leaking and dumping engine coolant (aka antifreeze) in both the A/C evaporator drain tube and on our Previa's passenger side floor carpeting (yuck!).

So, using Tim's excellent write-up, which can be found at http://www.toyotavantech.com/forum/s...-a-heater-core , we were able to successfully replace the leaky heater core with a new, aftermarket heater core. We followed Tim's "cheater heater core replacement", except we chose to cut through the plastic glove box rather than heating it and trying to deform it.

Below are some observations/suggestions for those looking to do this heater core replacement.

* We purchased an aftermarket heater core for our 1993 Previa. It was about $90 from NAPA and was made of Aluminum, although they had to special order it as it was not stocked anywhere in Texas! It was a Spectra Premium brand, even though it's sold under the NAPA name, and it came with a 1 year warranty. However, you end up having to cut the heater core's existing inlet/outlet tubes if you are using Tim's "cheater" heater core replacement method and therefore the warranty no longer applies. The fact that you have to cut the heater core's tubes to reinstall means you really shouldn't waste your money on an OEM heater core that is 3 times the price if you don't get the benefit of the warranty.

* We had a "black box" mounted directly underneath the glove box that had to be removed, something that didn't show up in Tim's write-up. It's believed to be part of the 'premium' stereo system for those Previa's that had the nicer sound systems.

* We used a Dremel with metal cutting discs to cut through the existing heater core copper tubing in order to remove it. We did not have Tim's air saw and a hacksaw would take way too long (I know, I tried).

* Before starting I drained our Previa's engine coolant completely using both the Radiator draincock, as well as the engine block coolant drain plug. The engine block coolant drain plug is hard to see/find, but it's near where the engine oil drain plug is and is tucked up in that area. It was a 10mm bolt that was silver colored, if that helps. The picture in the Previa FSM does not help much in finding it.

* After replacing the heater core I flushed the engine coolant system with distilled water, then filled it with Zerex Asian 50/50 pre-mixed engine coolant. It's the closest engine coolant to the Toyota "Red" that I could find locally (at NAPA)...it was either that or Prestone, and I wanted to go with as close to the Toyota "Red" coolant as possible.

* We decide to cut the plastic glove box, rather than use heat to deform it only because 1) we didn't have a heat gun/hair dryer/blow torch/etc, and 2) if we ever needed to replace this heater core again, we can just take off the glove compartment again. Yes, there is tape involved, along with some other plastic repairs, but it's compromise and well worth the $600 - $800 we saved in labor to have a dealer tear the dash apart and potentially break something plastic in a vehicle that is over 23 years old!

Hope this helps!!

[Kurtanius21]

Nice. Thanks for the write up. Why exactly does the heater core need to be replaced? Why would the heater core itself need to be replaced? Isn't it just a solid piece of metal? Is it the interface between the rubber hoses and the heater core? I never understood why these things need to be replaced. How many hours did it take you to finish this job?

[timsrv]

Why would the heater core itself need to be replaced? Isn't it just a solid piece of metal?

The heater core is basically a small radiator that's mounted inside the "HVAC suitcase" under your dash. Coolant from the engine is circulated through the inside of it, and air from the cabin fan motor is blown through the fins. Heat is exchanged from the coolant to the air, and this is where your cabin heat comes from. There are little trap doors you control with the levers to route the air through to the floor and/or up through the defrost ducts. Since heater cores are basically little radiators, they can spring leaks (just like their big brothers can). When heater cores leak, they can be a real problem because coolant is now leaking inside under your dash. This also increases humidity (a lot) and turns defrosters into "frosters" (steam that smells like antifreeze covers the inside of your windshield when you turn on the defroster). Of course the carpets get wet and stained with coolant too. In short, nothing good comes from a leaky heater core. Tim