The Limit Switch on my Frigidaire 90 upflow furnace is malfunctioning. As a result, I am getting no ignition--no flame. I replaced the igniter, and no difference. The blower and all else seems to be functioning properly. Any suggestions?

Do you know which limit is fualty? How do you know it is a limit problem? If the limit is open, you will not get power to the igniter, so replacing that was most likely money wasted. If you know where your limits are located, you can test them with a multimeter. Just kill power to the furnace, unhook the wires to the limits, and check for continuity across the two terminals. If no continuity, then the limit is open, and needs to be replace, or manually reset (if it's a resetable limit). If you have cont, then move on to the next limit. Please let me know what you find.

If you can post pics of the inside of your furnace, I may be able to help you locate limits etc.