Q&A

 Technician

Its most common actually to lose low speeds and only have high. I would look into your blower motor resistor pack, this is what gives you the different speeds, they are usually around 20-30 bucks at your local parts store, visit our website for FREE part and labor cost calculator www.elstonauto.com

 Master

Your 1999 Chevrolet Tahoe uses a high blower relay for the high speed operation of the HVAC blower motor. The relay is mounted on the heater box behind the glove box. The fault could be with the blower switch, the relay or a connection. I would recommend to begin diagnoses at the relay. You will need a wiring diagram and a test light for proper diagnoses.