I live at a high altitude and love to use my slow cooker, but I don't think the meals are coming out as expected when I follow the recipes. Do I need to adjust the recipes for high altitudes?
It really depends on the length of time recommended. Due to the usual long length (>4 hours) of slow-cooker recipe cook times most elevation differences would be negligible. However if a recipe calls for a cook time of less than 4 hours you may see some foods not cooking as usual. Legumes might especially be sensitive to this as they take a very long time to cook completely. Below is a table from Wikipedia on elevation vs water boiling temperatures.
Altitude, m Boiling point of water, °C
(0ft) 100 (212°F)
(984.25ft) 99.1 (210.3°F)
(1968.5ft) 98.1 (208.5°F)
(3280.8ft) 96.8 (206.2°F)
(6561.68ft) 93.3 (199.9°F)
(13123.36ft) 87.3 (189.1°F)
(19685.04ft) 81.3 (178.3°F)
(26246.72ft) 75.5 (167.9°F)
You may need to experiment with longer cook times for foods that you are having trouble with.
The first adjustment you can make for altitude is to cook something to a desired internal temperature rather than just "time and temperature". Your pot roast is done at an internal temperature of 160°F regardless of your altitude.
The real impact of a 'low and slow' technique is that at altitude your liquid will evaporate more quickly at the same temp, since that liquid is a heat transfer medium for most slow cooking, you will need more of it. You should add more water at the beginning or be prepared to add more water throughout the cooking time.