Sunday, September 4, 2011

Dead Dryer and Noisy Refrigerator

Two appliance issues I've fixed lately, not super interesting, but may be useful anyway. I don't fix appliances very often, so I usually do some head-scratching at some point.

1. Kenmore Dryer - A friend bought a new (used) washer and dryer to replace their old, non-functioning ones. after hauling the old ones up the side of a hill and the new ones down it, they discovered the dryer did nothing. Not wanting to haul it back up, they called me. I had him check a few things over the phone, but really didn't learn anything from that. It didn't appear to be getting power.

In hindsight I should have checked the door switch sooner, but I was stuck on a no-power train of thought. It only took a few minutes anyway, thankfully they're not as complicated as cars.

  • With the back cover off I verified the thermal fuse was OK and I definitely had power there. 
  • After a great deal of head scratching I thought it seemed like something had come unplugged, the door light wasn't on when the door was open and the wires to the switch were the only ones I couldn't see. 
  • Most dryers you pull forward and then up to open the top. They swing up on little spring clips that let it move forward enough to clear the front clips. Popping the lid up it became apparent that somehow the wires going to the door switch had come apart at the connector. I really don't know how it separated, it clipped back together firmly enough I didn't think it just popped apart on it's own. But,it's working now.
  • Model # 110.76642500 or 110.7163102 - I have two model numbers written down, not sure which is right.

2. Freezer on bottom refrigerator - My grandparents refrigerator started making funny noises, I thought sounded like bad fan bearings (I could hear it over the phone, sounded really bad).

  • At first I thought it was the fan on the outside, underneath the machine, but besides being very dusty, it make no unusual noises. 
  • That one eliminated left the one inside that circulated cold air through the refrigerator. After removing everything that blocked access to it (and there was a lot in the way) I could see the fan. It's bearings were also OK. So I plugged it back in, hoping to see something change, and did I ever. 
  • It seems that ice builds up in the passage between the refrigerator and freezer. Every once and a while it breaks free, falling back down the passage onto the fan, which flings it at my face. 
  • I'm blaming it on a spell of high humidity and poor design. If something deflected the ice away from the fan it wouldn't have to grind it up with it's little plastic blade. or if the fan was located at the top the ice would fall away from it, like a freezer on top model. 

Dodge 46RE First and Second Gears Only

A friend got a deal on a older Dodge 4x4 truck. It ran great, drove fine except it wouldn't shift past 2nd.
The possibilities are as follows: 
  • Speed sensor
  • Electrical Wiring
  • PWM Solenoid / pressure sensor (typically replaced together)
  • Computer
  • Internally broken parts
A little background:
The Dodge 4xRE RWD transmissions are descendents of an earlier design. Before computer controls they used a centrifugal governor and throttle cable to control shifts. When GM and Ford went to computer controls they used a PWM (pulse width modulation) solenoid for mainline pressure and solenoids for shifting, eliminating the throttle and governor systems. Dodge left the throttle cable, and replaced the mechanical governor with a PWM solenoid and a pressure sensor controlled by the computer. With the exception of 4th, as it is independently controlled by the computer via it's own solenoid, the 4xRE's all depend on the governor pressure to know which gear to be in.

We were fortunate to have a 44RE core to steal parts from.
First was getting it here, it would be a long drive in 2nd, so I had him pull the electrical connector off, hoping for third. I didn't know if this would work or not, depending what was wrong, but fail-safe is third so it was worth a try. It worked, so the actual transmission was OK, just something in the controls. (Note: even with the electric off, if it was still stuck in 2nd, it could still have been the governor solenoid stuck)

  1. The speed sensor is a 1 minute swap, we had one, so that was the place to start. But it made no difference.
  2. A visual inspection of the wiring showed no problems, and we didn't have a spare computer to try (that would be #4 anyway).
  3. The Governor solenoid / pressure sensor combo is a very common problem with these transmissions, what happens is over time they get fine metal shavings in them until the solenoid sticks (it is a magnet). This was my guess from the start, but you have to drop the pan to get too them, so don't overlook something obvious. We dropped the pan, swapped them with the ones off my junk tranny (Note: these are such a common problem it is recommended to replace with new every time. He didn't have the money for new, so used it was) That solved it, had 4 forward gears and he was happy.
  1. While you have to drop the pan to get to the sensors, they are east to access, being bolted to the bottom of the valve body, on their own little block of aluminum. 
  2. KEEP IT CLEAN! Any dirt is very bad inside a valve body.
  3. USE A TORQUE WRENCH ON THE VALVE BODY! They are particularly sensitive to that sort of thing. (35in lbs. I think)
  4. There is an alternative setup for this using a GM PWM solenoid. They claim it stops this sort of thing from ever happening again. I haven't tried one yet, but definitely would, especially on a tranny that has given me problems.
  5. Don't overlook the obvious, Yes, I was right this time, but it could have been something else. Like the speed sensor, and if I'd gone with my gut and been wrong, I'd have spent an hour fixing something that would have taken a minute.
  6. Most vehicles fail-safe to third (actually direct drive, could be 4th in a 5 or 6 speed auto tranny) in drive, and the manual 1st, 2nd, etc. still work. You can manually shift these to prevent damage - Fail-safe third is third all the time, you will eventually damage something if you don't.
  7. The background may be over-simplified, but contains enough information for my purposes.