I did the heater core/evaporator core replacement about 2 weeks ago on my '97 3500 Diesel. It most certainly was a bugger of a job but wasn't too bad as long as you have a fair amount of time because you will get frustrated, at times. It took me several days because I wanted to be thorough, not do it again for several years, hopefully, and I work shorter days now (newly retired). A few more thoughts to add all of the excellent posts I read through.
My heater core went out during the summer but didn't really have time because our youngest daughter was getting married in August so I just bypassed the heater with a piece of hose. Glad I did because then the evaporator core went out and their both in the same housing. We were down in Yuma and a repair shop wanted over $650 for labor for the job so there's good incentive! Need the evaporator here and the heater core in Oregon. Joe Donnelly's article in issue 46, page 12-15 is real good, as far as it goes, which is heater core replacement. Joe has a helpful list at the end of his article with socket sizes. If I was in that deep, I would go in and check the condition of the evaporator core (same age). If you notice a reduced volume of air flow on the 4th speed of your fan, it may well be because the blower air goes through the evaporator core before the heater core. Besides leaking (green dye from AC shop helps locate), our evaporator core was almost ½ plugged with leaf debris and, apparently, dog hair from the first owner's (probably running on recirculated air from the cab).
Parts- Did some checking around, NAPA had a good price for a heater core ($107 and good being relative) and got it in one day but I didn't like the aluminum core and “flex” crimped fittings that swivel (probably fits other trucks). It may well work fine for quite some time but didn't want to wonder if the “swivel” gaskets would hold up more than a couple of years. Aluminum tubes were also roughly bent and gouged from their tube bender (China). AC shop part prices were between NAPA and Dodge but the “guaranteed” brass core wound up being same aluminum “flex” as NAPA after 3 day wait, GRRR. Dodge core (Taiwan) was way too expensive at $227 (they know what the competition core is) but it is a “direct” replacement for the old one with a nice core and nicely soldered copper tubes (saving on labor helped price of core!). Tubes were bent perfect and a little longer which makes for easier hookup. It also had all of the foam padding glued on so it will fit tight and stay put so it won't vibrate around and leak over time. Be careful tightening the clamp at the tube/core solder connection so you don't build in a strain that could leak, over time. NAPA evaporator core ($158) was cheaply made and one tube was bent about 15 degrees off needed bend (not much room for incorrect bend hookup on this core) and again, no padding. Dodge core was $198 but perfect replacement with padding and tube insulation just like the original (this core was even made in the USA!!). Hate the outrageous prices (especially for foreign cheap labor parts) compared to the old days but what can you do (a lot cheaper than new truck payments).
I didn't have a problem with dropping the steering column only onto the seat but really look ahead for strained wires (especially if you have added accessories) and the metal plate below the column also needs to be removed because sharp edges press against column wires with it dropped. I didn't have a (major,grrr) problem with the 5 dash board top 10mm screws (thin deep wall sockets and extensions essential!) on removal but trouble with center screw on reinstall because dash was warped a little low in the center. Filing point on screw (and choice cuss words) got it back in (no squeaks, old Ford dash had bad squeaks!). Figure out how the cheap O-ring tool works, if you don't know already, before you remove refrig lines (pretty simple, once you know). Be very careful with seal areas of tubing (I slightly gouged one tube end seal area I couldn't see on disconnect and had to polish out with fine emory and crocus). Any flaw could cause O-ring leak. “Always” use new O-rings of right compound on refrig tubes and lube them with PAG oil (tubing “snaps” together pretty slick). I put 2 oz directly in the inlet of the evaporator core tube and 3 ozs in the new accumulator (Dodge book says 4 and AC shop said 2 so I put in 3 into the “inlet” tube). You have to remove the accumulator to access heater box nuts so replaced (AC shop said accumulator only good for 5/6 years (hmm) but want system to work good after all this. Again, NAPA part ($63, Dodge $126, double, hmmm) looked cheap (aluminum & China made may be OK but can't see inside) but incorrect angle on outlet tube that may or may not have hooked up. You don't want unnecessary leaks, vacuuming and recharging AC way too expensive for that! Remove and clean fixed orifice screen and regulator in condenser outlet tube end. Reach straight in “gently” with long needle nose pliers with “real” good serrations on the jaws, (don't bugger up ID of tube, sealing area!), it will come out hard at first because of “O” rings. It is critical to keep water and crude out of all tubing and internal AC parts!! Keep tubing and parts clean and sealed until just ready for assembly!
Holding up right end dash board to remove and install heater/AC box is absolutely necessary! I was working outside so rigged a 2 X 4 across top of cab and open right door. Using rope and bungies, I held right dash end about 8 inches up and 6 inches back beyond dash “roll back” position to just have enough room to remove and install box (still a &@*_, watch all vacuum hoses, especially “two” on actuator on floor board and be gentle with temp control cable removal!). Left end of dash will behave, if you loosen left pivot bolt well and watch for wire strains around steering column and dash area.
Take your time and thoroughly clean the box of crude. Also I took the time to clean crude from cowl and wiper motor area or it may wind up in your new parts. I have pictures if anyone is interested or wants more info. Sorry for the length of this email but found other Members details very helpful. We now have Great AC and heat!! Take your time, think about the money your saving and good luck!
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